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Tinoshuma nezvemhedzisiro inoshamisa ye photovoltaic muYBa2Cu3O6.96 (YBCO) ceramic iri pakati pe50 ne300 K inokonzerwa nechiedza cheblue-laser, icho chine chekuita zvakananga ne superconductivity yeYBCO uye YBCO-metallic electrode interface. Kune polarity reversal ye open circuit voltage Voc uye short circuit current Isc apo YBCO inoshanduka kubva ku superconducting kuenda ku resistive state. Tinoratidza kuti kune electrical potential kuburikidza ne superconductor-normal metal interface, iyo inopa simba rekuparadzanisa ma photo-induced electron-hole pairs. Iyi interface potential inotungamira kubva kuYBCO kuenda ku metal electrode apo YBCO iri superconducting uye inochinja kuenda kune imwe nzira apo YBCO yava nonsuperconducting. Kwakatangira potential kunogona kunge kwakabatana ne proximity effect pa metal-superconductor interface apo YBCO iri superconducting uye kukosha kwayo kunofungidzirwa kuva ~10–8 mV pa50 K ne laser intensity ye502 mW/cm2. Kusanganiswa kwechinhu chemhando yep-YBCO chiri mumamiriro akajairwa nechinhu chemhando yen-Ag-paste inoumba mubatanidzwa we quasi-pn uyo unokonzera maitiro e photovoltaic eYBCO ceramics pakupisa kwakanyanya. Zvatakawana zvinogona kugadzirira nzira yekushandisa zvishandiso zvitsva zve photon-electronic uye kuratidza zvakawanda nezvemhedzisiro yepedyo pane superconductor-metal interface.
Voltage inokonzerwa nemufananidzo muma superconductors ane tembiricha yakakwira yakashumwa kutanga kwema1990 uye yakaferefetwa zvakanyanya kubvira ipapo, asi hunhu hwayo uye mashandiro ayo hazvina kugadziriswa1,2,3,4,5. Mafirimu matete eYBa2Cu3O7-δ (YBCO)6,7,8, kunyanya, anodzidzwa zvakanyanya muchimiro chesero re photovoltaic (PV) nekuda kwegedhi rayo resimba rinogadziriswa9,10,11,12,13. Zvisinei, kuramba kwakanyanya kwe substrate kunogara kuchitungamira mukushanda kwakaderera kwekushandura kwechishandiso uye kufukidza hunhu hwePV hweYBCO8. Pano tinotaura nezvemhedzisiro inoshamisa ye photovoltaic inokonzerwa ne blue-laser (λ = 450 nm) kuvhenekerwa muYBa2Cu3O6.96 (YBCO) ceramic iri pakati pe50 ne300 K (Tc ~ 90 K). Tinoratidza kuti mhedzisiro yePV ine chekuita zvakananga ne superconductivity yeYBCO uye hunhu hweYBCO-metallic electrode interface. Pane polarity reversal ye open circuit voltage Voc uye short circuit current Isc kana YBCO yachinja kubva pa superconducting phase kuenda ku resistive state. Zvinofungidzirwa kuti pane electrical potential kuburikidza ne superconductor-normal metal interface, iyo inopa simba rekuparadzanisa kwema photo-induced electron-hole pairs. Iyi interface potential inotungamira kubva kuYBCO kuenda ku metal electrode kana YBCO iri superconducting uye inochinja kuenda kune imwe nzira kana sample isingaite superconducting. Kwakatangira potential kunogona kunge kwakabatana ne proximity effect14,15,16,17 pa metal-superconductor interface kana YBCO iri superconducting uye kukosha kwayo kunofungidzirwa kuva ~10−8 mV pa50 K ne laser intensity ye502 mW/cm2. Musanganiswa we p-type material YBCO pa normal state ne n-type material Ag-paste inoumba, pamwe, quasi-pn junction iyo inokonzera PV behavior yeYBCO ceramics pakupisa kwakanyanya. Zvatakaona zvakawedzera kujekesa mavambo emhedzisiro yePV muzvigadzirwa zveYBCO zvinoshandisa kupisa kwakanyanya uye zvinogadzira nzira yekushandiswa kwayo muzvishandiso zve optoelectronic zvakaita se fast passive light detector nezvimwewo.
Mufananidzo 1a–c unoratidza kuti hunhu hweIV hweYBCO ceramic sample pa50 K. Pasina chiedza chechiedza, voltage pamusoro pesample inoramba iri pa zero nekuchinja kwemagetsi, sezvinotarisirwa kubva kune superconducting material. Mhedzisiro ye photovoltaic inoonekwa kana laser beam yakananga ku cathode (Mufananidzo 1a): ma IV curves akafanana ne I-axis anofamba achidzika nekuwedzera kwesimba re laser. Zviri pachena kuti kune negative photo-induced voltage kunyangwe pasina chero current (inowanzonzi open circuit voltage Voc). Zero slope ye IV curve inoratidza kuti sample ichiri superconducting pasi pe laser illumination.
(a–c) uye 300 K (e–g). Kukosha kweV(I) kwakawanikwa nekutsvaira magetsi kubva pa −10 mA kusvika pa +10 mA mu vacuum. Chikamu chedata rekuyedza chete ndicho chinopihwa kuti zvijekeswe. a, Hunhu hwemagetsi eYBCO hwakayerwa ne laser spot iri pa cathode (i). Ma IV curves ese ari mitsetse yakatwasuka inoratidza kuti sampuro ichiri kuita superconducting ne laser irradiation. Curve inofamba ichidzika ne laser intensity inowedzera, zvichiratidza kuti pane mukana wekusagadzikana (Voc) pakati pema voltage leads maviri kunyangwe pasina zero current. Ma IV curves anoramba asina kuchinja kana laser yakananga pakati pe sampuro pa ether 50 K (b) kana 300 K (f). Mutsetse wakatwasuka unokwira kumusoro sezvo anode yavhenekerwa (c). Muenzaniso we schematic we metal-superconductor junction pa50 K unoratidzwa muna d. Hunhu hwemagetsi emagetsi eYBCO pa300 K akayerwa nelaser beam yakanongedzwa pa cathode ne anode anopiwa mu e ne g zvakateerana. Kusiyana nemhedzisiro iri pa50 K, kutsvedza kwemitsara yakatwasuka kusiri zero kunoratidza kuti YBCO iri mumamiriro akajairika; kukosha kweVoc kunosiyana nekupenya kwechiedza munzira yakatarisana, zvichiratidza nzira yakasiyana yekuparadzanisa charge. Chimiro che interface chinogona kuitika pa300 K chinoratidzwa mu hj Mufananidzo chaiwo wemuenzaniso une leads.
YBCO ine okisijeni yakawanda mu superconducting inogona kutora chiedza chezuva chakazara nekuda kwemusiyano wayo mudiki wesimba (Eg)9,10, nokudaro ichigadzira maerekitironi-maburi maviri (e-h). Kuti ugadzire voltage yakavhurika yeVoc nekunyudzwa kwemaphoton, zvakakosha kuparadzanisa maeh maviri akagadzirwa ne photo-generated musati maita recombination18. Iyo negative Voc, kana tichienzanisa ne cathode ne anode sezvakaratidzwa mu Fig. 1i, inoratidza kuti pane simba remagetsi pakati pe metal-superconductor interface, iyo inokwevera maerekitironi ku anode uye maburi ku cathode. Kana zvakadaro, panofanirawo kuve ne potential inonongedza kubva ku superconductor kuenda ku metal electrode pa anode. Nekuda kweizvozvo, Voc yakanaka inowanikwa kana nzvimbo yemuenzaniso iri pedyo ne anode yakavhenekerwa. Uyezve, hapafanirwe kuve ne photo-induced voltages kana laser spot ichinongedzera kunzvimbo dziri kure nemaerekitironi. Ndizvo zvazviri sezvazvinogona kuonekwa kubva ku Fig. 1b,c!.
Kana chiedza chikafamba kubva pa cathode electrode kuenda pakati pemuenzaniso (anenge 1.25 mm kubva painterfaces), hapana shanduko yema IV curves uye hapana Voc inogona kuonekwa nekuwedzera kwe laser intensity kusvika pahuwandu hwakanyanya huripo (Mufananidzo 1b). Zviri pachena kuti mhedzisiro iyi inogona kuverengerwa kuhupenyu hushoma hwevatakuri ve photo-induced uye kushaya simba rekuparadzanisa mumuenzaniso. Ma electron-hole pairs anogona kugadzirwa pese painovhenekerwa sample, asi mazhinji e e-h pairs achaparadzwa uye hapana photovoltaic effect inoonekwa kana laser spot ikawira panzvimbo dziri kure nechero electrodes. Kufambisa laser spot kuenda kuma anode electrodes, ma IV curves akafanana ne I-axis anokwira kumusoro nekuwedzera kwe laser intensity (Mufananidzo 1c). Nzvimbo yemagetsi yakafanana iripo mu metal-superconductor junction pa anode. Zvisinei, metallic electrode inobatana ne positive lead ye test system panguva ino. Maburi anogadzirwa ne laser anosundirwa ku anode lead saka Voc yakanaka inoonekwa. Mhedzisiro yakapihwa pano inopa humbowo hwakasimba hwekuti zvechokwadi kune mukana wekunongedzera kubva ku superconductor kuenda ku electrode yesimbi.
Mhedzisiro ye photovoltaic muYBa2Cu3O6.96 ceramics pa300 K inoratidzwa muFig. 1e–g. Pasina chiedza chechiedza, IV curve yemuenzaniso imutsara wakatwasuka unoyambuka kwawakabva. Mutsetse uyu wakatwasuka unokwira kumusoro wakaenzana newawo wekutanga nekuwedzera kwesimba re laser richipenya pa cathode leads (Fig. 1e). Kune zviitiko zviviri zvinodzivirira zvinofarirwa nechinhu che photovoltaic. Mamiriro e short-circuit anoitika kana V = 0. Muchiitiko ichi chinonzi short circuit current (Isc). Muchiitiko chechipiri chinodzivisa i open-circuit condition (Voc) inoitika kana R→∞ kana current iri zero. Mufananidzo 1e unoratidza zvakajeka kuti Voc yakanaka uye inowedzera nekuwedzera kwesimba rechiedza, kusiyana nemhedzisiro inowanikwa pa50 K; nepo Isc isina kunaka ichionekwa ichiwedzera muhukuru nechiedza chechiedza, maitiro akajairika emasero ezuva akajairwa.
Saizvozvowo, kana danda relaser rakanongedzwa kunzvimbo dziri kure nema electrodes, V(I) curve haina chekuita nehukuru hwelaser uye hapana photovoltaic effect yakaonekwa (Mufananidzo 1f). Kufanana nekuyera pa50 K, ma IV curves anoenda kune rimwe divi sezvo anode electrode ichipiswa nemwaranzi (Mufananidzo 1g). Mhedzisiro iyi yese yakawanikwa kune iyi YBCO-Ag paste system pa300 K ine laser yakapiswa panzvimbo dzakasiyana dzemuenzaniso inoenderana neinterface potential yakatarisana neiyo yakaonekwa pa50 K.
Mazhinji emaerekitironi anoungana muCooper pairs mu superconducting YBCO pasi pe transition tembiricha yayo Tc. Ari mu metal electrode, maerekitironi ese anoramba ari mu singular form. Kune density gradient yakakura yemaerekitironi ese ari maviri uye maCooper pairs ari pedyo ne metal-superconductor interface. Maerekitironi akawanda anotakura singular ari mu metallic material achapararira munzvimbo ye superconductor, nepo maCooper-pairs mazhinji ari mu YBCO region achapararira munzvimbo ye metal. Sezvo maCooper maviri anotakura macharges akawanda uye aine kufamba kukuru kupfuura maerekitironi e singular achipararira kubva kuYBCO kuenda kunzvimbo ye metallic, maatomu ane positive charge anosara, zvichikonzera electric field munzvimbo ye space charge. Kutungamira kwe electric field iyi kunoratidzwa mu schematic diagram Mufananidzo 1d. Incident photon illumination iri pedyo ne space charge region inogona kugadzira eh pairs dzichaparadzaniswa uye kutsvairwa dzichigadzira photocurrent munzira ye reverse-bias. Kana maerekitironi angobuda mumunda we electrical build-in, anoungana kuita ma pairs uye anoyerera kuenda kune imwe electrode pasina resistance. Muchiitiko ichi, Voc inopesana ne polarity yakatoiswa uye inoratidza kukosha kwakashata kana danda relaser richinongedzera kunzvimbo yakatenderedza electrode isina kunaka. Kubva pakukosha kweVoc, kugona kunopfuura neinterface kunogona kufungidzirwa: daro riri pakati pema voltage leads maviri d i ~5 × 10−3 m, ukobvu hwe interface yesimbi-superconductor, di, hunofanira kunge hwakafanana nehurefu hwekubatana kweYBCO superconductor (~1 nm)19,20, tora kukosha kweVoc = 0.03 mV, potential Vms pa interface yesimbi-superconductor inoongororwa kuva ~10−11 V pa50 K ne laser intensity ye502 mW/cm2, uchishandisa equation,
Tinoda kusimbisa pano kuti voltage inokonzerwa nephoto-induced haigoni kutsanangurwa nephoto thermal effect. Zvakaonekwa nekuyedza kuti Seebeck coefficient ye superconductor YBCO iSs = 021. Seebeck coefficient ye copper lead wires iri pakati pe SCu = 0.34–1.15 μV/K3. Tembiricha ye copper wire panzvimbo ye laser inogona kukwidzwa ne 0.06 K ine laser intensity yakanyanya inowanikwa pa 50 K. Izvi zvinogona kugadzira thermoelectric potential ye 6.9 × 10−8 V iyo iri three orders magnitude diki pane Voc yakawanikwa muFig 1 (a). Zviri pachena kuti thermoelectric effect idiki kwazvo kutsanangura mhedzisiro yekuyedza. Kutaura zvazviri, kusiyana kwetembiricha nekuda kwe laser irradiation kwaizonyangarika muminiti isingasviki imwe kuitira kuti mupiro we thermal effect ugone kufuratirwa zvakachengeteka.
Kushanda kweYBCO pakupisa kwemumba kunoratidza kuti pane nzira yakasiyana yekuparadzanisa machaji. Superconducting YBCO iri mumamiriro akajairwa imhando yep-type ine maburi sechaja inotakura22,23, nepo metallic Ag-paste ine hunhu hwemhando yen-type. Kufanana ne pn junctions, kupararira kwemaerekitironi mu silver paste nemaburi muYBCO ceramic kuchagadzira munda wemagetsi wemukati unonongedzera kuYBCO ceramic panzvimbo inopindirana (Mufananidzo 1h). Ndiwo munda wemukati uyu unopa simba rekuparadzanisa uye unotungamira kune Voc yakanaka uye negative Isc yeYBCO-Ag paste system pakupisa kwemumba, sezvakaratidzwa muMufananidzo 1e. Neimwe nzira, Ag-YBCO inogona kugadzira p-type Schottky junction iyo inotungamirawo kune interface potential ine polarity yakafanana neyakaratidzwa pamusoro apa24.
Kuti tiongorore maitiro ekushanduka-shanduka kwehunhu hwe photovoltaic panguva yekuchinja kwe superconducting kweYBCO, ma IV curves emuenzaniso pa 80 K akayerwa ne laser intensities dzakasarudzwa dzinovheneka pa cathode electrode (Mufananidzo 2). Pasina laser irradiation, voltage pamusoro pemuenzaniso inoramba iri pa zero pasinei ne current, zvichiratidza mamiriro e superconducting emuenzaniso pa 80 K (Mufananidzo 2a). Kufanana nedata rakawanikwa pa 50 K, ma IV curves akafanana ne I-axis anofamba achidzika ne laser intensity inowedzera kusvika Pc yasvika pa critical value. Pamusoro pe critical laser intensity iyi (Pc), superconductor inochinja kubva pa superconducting phase kuenda pa resistive phase; voltage inotanga kuwedzera ne current nekuda kwekuonekwa kwe resistance mu superconductor. Nekuda kweizvozvo, IV curve inotanga kusangana ne I-axis ne V-axis zvichitungamira ku negative Voc ne positive Isc pakutanga. Iye zvino muenzaniso unoita seuri mumamiriro chaiwo umo polarity yeVoc ne Isc inonyanya kunzwa ku light intensity; Nekuwedzera kudiki kwesimba rechiedza, Isc inoshandurwa kubva pane zvakanaka kuenda pane zvakaipa uye Voc kubva pane zvakaipa kuenda kune zvakanaka, zvichipfuura mavambo (kunzwa kwakanyanya kwehunhu hwe photovoltaic, kunyanya kukosha kweIsc, kuenda kune chiedza chechiedza kunogona kuonekwa zvakajeka muMufananidzo 2b). Pasimba re laser rakakwirira riripo, ma IV curves anoda kufanana, zvichiratidza mamiriro akajairwa emuenzaniso weYBCO.
Nzvimbo ye laser spot iri panzvimbo yakatenderedza ma cathode electrodes (ona Mufananidzo 1i). a, IV curves dzeYBCO dzakapiswa ne laser intensities dzakasiyana. b (kumusoro), Laser intensity dependence ye open circuit voltage Voc uye short circuit current Isc. Ma Isc values haagone kuwanikwa pa low light intensity (< 110 mW/cm2) nekuti IV curves dziri parallel ne I-axis kana sample iri mu superconducting state. b (pasi), differential resistance sebasa re laser intensity.
Kuenderana kweVoc neIsc nelaser intensity pa80 K kunoratidzwa muMufananidzo 2b (kumusoro). Hunhu hwephotovoltaic hunogona kukurukurwa munzvimbo nhatu dzechiedza. Dunhu rekutanga riri pakati pe0 nePc, umo YBCO iri superconducting, Voc iri negative uye inodzikira (absolute value inowedzera) nechiedza ichisvika padiki paPc. Dunhu rechipiri rinobva paPc kuenda kune rimwe critical intensity P0, umo Voc inowedzera nepo Isc ichiderera nechiedza chinowedzera uye zvese zvinosvika zero paP0. Dunhu rechitatu riri pamusoro peP0 kusvika mamiriro akajairwa eYBCO asvika. Kunyangwe ese Voc neIsc zvichisiyana nechiedza chakasimba nenzira imwecheteyo iri mudunhu 2, zvine polarity yakapesana pamusoro pecritical intensity P0. Kukosha kweP0 kuri pakuti hapana photovoltaic effect uye charge separation mechanism inoshanduka qualitatively panguva iyi chaiyo. Sample yeYBCO inova non-superconducting muhuwandu uhwu hwechiedza chakasimba asi mamiriro akajairwa asati asvika.
Zviri pachena kuti hunhu hwe photovoltaic hwesystem hwakabatana zvakanyanya ne superconductivity yeYBCO uye shanduko yayo ye superconducting. Kuramba kwakasiyana, dV/dI, yeYBCO kunoratidzwa muMufananidzo 2b (pasi) sebasa re laser intensity. Sezvambotaurwa, build-in electric potential mu interface nekuda kweCooper pair diffusion points kubva ku superconductor kuenda kusimbi. Zvakafanana nezvinoonekwa pa50 K, photovoltaic effect inowedzerwa nekuwedzera laser intensity kubva pa0 kuenda kuPc. Kana laser intensity yasvika pamusoro pePc zvishoma, IV curve inotanga kutsvedza uye resistance yemuenzaniso inotanga kuoneka, asi polarity ye interface potential haisati yachinja. Mhedzisiro ye optical excitation pa superconductivity yakaongororwa munzvimbo inoonekwa kana iri pedyo neIR. Kunyange hazvo maitiro ekutanga ari ekuparadzanisa Cooper pairs uye kuparadza superconductivity25,26, mune dzimwe nguva superconductivity transition inogona kuwedzerwa27,28,29, zvikamu zvitsva zve superconductivity zvinogona kutokonzereswa30. Kusavapo kwe superconductivity paPc kunogona kunzi kwakakonzerwa nekuputsika kwepair inokonzerwa ne photo-induced. Pa point P0, potential mu interface inova zero, zvichiratidza kuti charge density kumativi ese e interface inosvika padanho rimwe chete pasi pesimba iri rekupenya kwechiedza. Kuwedzera kwakawanda kwe laser intensity kunoita kuti maCooper pairs akawanda aparare uye YBCO inoshandurwa zvishoma nezvishoma kuita p-type material. Panzvimbo pekupararira kwema electron neCooper pair, chimiro che interface ikozvino chinosarudzwa nekupararira kwema electron nehole izvo zvinotungamira ku polarity reversal ye electrical field mu interface uye nekudaro Voc yakanaka (enzanisa Fig.1d, h). Pa high very laser intensity, differential resistance yeYBCO saturates kusvika pa value inoenderana ne normal state uye ese Voc neIsc zvinowanzo chinja linearly ne laser intensity (Fig. 2b). Izvi zvinoratidza kuti laser irradiation pa normal state YBCO haizochinje resistivity yayo uye chimiro che superconductor-metal interface asi inowedzera chete concentration yema electron-hole pairs.
Kuti tiongorore mhedzisiro yekupisa pahunhu hwe photovoltaic, sisitimu yesimbi-superconductor yakavhenekerwa pa cathode ne blue laser ye intensity 502 mW/cm2. Ma IV curves akawanikwa patembiricha dzakasarudzwa dziri pakati pe50 ne300 K akapihwa muFig. 3a. Voltage ye open circuit Voc, short circuit current Isc uye differential resistance zvinogona kuwanikwa kubva kuma IV curves aya uye zvinoratidzwa muFig. 3b. Pasina chiedza chechiedza, ma IV curves ese akayerwa patembiricha dzakasiyana anopfuura mavambo sezvaitarisirwa (inset yeFig. 3a). Hunhu hwe IV hunochinja zvakanyanya nekuwedzera kwekupisa kana sisitimu yavhenekerwa ne laser beam yakasimba (502 mW/cm2). Patembiricha yakaderera ma IV curves imitsara yakatwasuka yakafanana neI-axis ine negative values yeVoc. Iyi curve inokwira kumusoro nekuwedzera kwekupisa uye zvishoma nezvishoma inoshanduka kuita mutsetse une nonzero slope pa critical temperature Tcp (Fig. 3a (kumusoro)). Zvinoita sekunge ma IV characteristic curves ese anotenderera kutenderedza poindi mu third quadrant. Voc inowedzera kubva pane negative value kuenda pane positive nepo Isc ichiderera kubva pane positive kuenda pane negative value. Pamusoro pe superconducting transition temperature yekutanga Tc yeYBCO, IV curve inochinja zvakasiyana netembiricha (pasi peMufananidzo 3a). Chekutanga, nzvimbo yekutenderera yema IV curves inotamira ku quadrant yekutanga. Chechipiri, Voc inoramba ichidzikira uye Isc inowedzera netembiricha inowedzera (kumusoro kweMufananidzo 3b). Chechitatu, kutsvedza kwema IV curves kunowedzera zvakananga netembiricha zvichikonzera positive temperature coefficient ye resistance yeYBCO (pasi peMufananidzo 3b).
Kuenderana nekupisa kwehunhu hwe photovoltaic kune system yeYBCO-Ag paste pasi pe502 mW/cm2 laser illumination.
Nzvimbo ye laser spot iri panzvimbo yakatenderedza ma cathode electrodes (ona Mufananidzo 1i). a, ma IV curves anowanikwa kubva pa50 kusvika 90 K (kumusoro) uye kubva pa100 kusvika 300 K (pasi) nekuwedzera kwekushisa kwe5 K ne20 K, zvichiteerana. Inset a inoratidza hunhu hweIV pakupisa kwakati wandei murima. Ma curves ese anoyambuka poindi yekutanga. b, open circuit voltage Voc uye short circuit current Isc (kumusoro) uye differential resistance, dV/dI, yeYBCO (pasi) sebasa rekupisa. Zero resistance superconducting transition temperature Tcp haipihwe nekuti iri pedyo zvakanyanya neTc0.
Kupisa kutatu kwakakosha kunogona kuonekwa kubva paMufananidzo 3b: Tcp, pamusoro payo YBCO isingaite superconducting; Tc0, apo Voc neIsc zvese zvinova zero uye Tc, tembiricha yekutanga yekuchinja kweYBCO isina laser irradiation. Pasi peTcp ~ 55 K, laser irradiated YBCO iri mu superconducting ine huwandu hwakawanda hweCooper pairs. Mhedzisiro ye laser irradiation ndeyekuderedza zero resistance superconducting transition tembiricha kubva pa89 K kusvika ~55 K (pasi peMufananidzo 3b) nekuderedza zero resistance superconducting transition tembiricha kubva pa89 K kusvika ~55 K (pasi peMufananidzo 3b) nekuderedza zero resistance superconducting transition tembiricha pamusoro pekugadzira photovoltaic voltage uye current. Kuwedzera kwekupisa kunoputsawo Cooper pairs zvichikonzera potential yakaderera mu interface. Nekuda kweizvozvo, kukosha kwakakwana kweVoc kuchava kudiki, kunyangwe simba rakafanana re laser illumination richishandiswa. Iyo interface potential ichava diki uye diki nekuwedzera kwekupisa uye inosvika zero paTc0. Hapana photovoltaic effect panzvimbo iyi yakakosha nekuti hapana munda wemukati wekuparadzanisa photo-induced electron-hole pairs. Kuchinja kwepolarity ye potential kunoitika pamusoro pekupisa uku kwakakosha sezvo huwandu hwe free charge muAg paste hwakakura kupfuura huri muYBCO iyo inodzoserwa zvishoma nezvishoma kuchinhu che p-type. Pano tinoda kusimbisa kuti polarity reversal yeVoc neIsc inoitika pakarepo mushure me zero resistance superconducting transition, zvisinei nechikonzero chekuchinja. Kucherechedza uku kunoratidza pachena, kekutanga, hukama huripo pakati pe superconductivity ne photovoltaic effects ine chekuita ne metal-superconductor interface potential. Hunhu hwe potential iyi mu superconductor-normal metal interface hwave huri kutsvagurudzwa kwemakumi emakore apfuura asi kune mibvunzo yakawanda ichiri kumirira kupindurwa. Kuyerwa kwe photovoltaic effect kunogona kuva nzira inoshanda yekuongorora ruzivo (sekusimba kwayo uye polarity nezvimwewo) ye potential iyi yakakosha uye nokudaro kujekesa mhedzisiro ye high temperature superconducting proximity.
Kuwedzera kwekupisa kubva paTc0 kuenda kuTc kunotungamira kuhuwandu hudiki hwemaCooper pairs uye kuwedzera kweinterface potential uye nekudaro Voc yakakura. PaTc huwandu hwemaCooper pair hunova zero uye kugona kwekuvaka mukati painterface kunosvika pakakwirira, zvichikonzera Voc yepamusoro uye minimum Isc. Kuwedzera nekukurumidza kweVoc neIsc (absolute value) muhurefu hwekupisa uku kunoenderana nekuchinja kwesuperconducting uko kunowedzerwa kubva kuΔT ~ 3 K kusvika ~ 34 K ne laser irradiation ye intensity 502 mW/cm2 (Mufananidzo 3b). Mumamiriro ezvinhu akajairwa ari pamusoro peTc, open circuit voltage Voc inoderera nekupisa (kumusoro kweMufananidzo 3b), zvakafanana ne linear behavior yeVoc yema normal solar cells zvichibva pa pn junctions31,32,33. Kunyangwe chiyero chekuchinja kweVoc nekupisa (−dVoc/dT), icho chinoenderana zvakanyanya ne laser intensity, chiri chidiki zvikuru pane che normal solar cells, tembiricha coefficient yeVoc yeYBCO-Ag junction ine order yakafanana neyema solar cells. Kubuda kwemvura kwepn junction yechinhu chezuva chemazuva ese kunowedzera nekupisa kuri kuwedzera, zvichikonzera kudzikira kweVoc sezvo kupisa kuri kuwedzera. Ma curve e linear IV akaonekwa kune iyi Ag-superconductor system, nekuda kwekutanga kugona kweinterface kudiki uye chechipiri kubatana kwe heterojunctions mbiri, zvinoita kuti zviome kuona kudonha kwemvura. Kunyange zvakadaro, zvinoita sekunge kuenderana kwekupisa kwakafanana kwemvura inobuda ndiko kunokonzera maitiro eVoc akaonekwa mukuyedza kwedu. Sekureva kwetsananguro, Isc ndiyo mhepo inodiwa kugadzira voltage isina kunaka kuti idzorere Voc kuitira kuti voltage yese ive zero. Sezvo kupisa kuri kuwedzera, Voc inova diki zvekuti magetsi mashoma anodiwa kuti igadzire voltage isina kunaka. Uyezve, kuramba kweYBCO kunowedzera zvakananga nekupisa kuri pamusoro peTc (pasi peMufananidzo 3b), izvo zvinoitawo kuti kukosha kweIsc kuve kudiki pakupisa kwakanyanya.
Cherechedza kuti mhedzisiro yakapihwa muMifananidzo 2,3 inowanikwa nekushandiswa kwelaser munzvimbo yakapoteredza ma electrodes e cathode. Kuyerwa kwadzokororwawo ne laser spot iri pa anode uye hunhu hwakafanana hwe IV uye hunhu hwe photovoltaic zvakaonekwa kunze kwekuti polarity yeVoc neIsc yakadzoserwa kumashure munyaya iyi. Ruzivo urwu rwese rwunotungamira kune nzira ye photovoltaic effect, iyo ine hukama hwakasimba ne superconductor-metal interface.
Muchidimbu, hunhu hweIV hwe laser irradiated superconducting YBCO-Ag paste system hwakayerwa semabasa ekupisa uye simba re laser. Mhedzisiro inoshamisa ye photovoltaic yakaonekwa muhuwandu hwekupisa kubva pa50 kusvika 300 K. Zvakaonekwa kuti hunhu hwe photovoltaic hunoenderana zvakanyanya ne superconductivity yeYBCO ceramics. Kuchinja kwe polarity kweVoc neIsc kunoitika pakarepo mushure mekuchinja kwe photo-induced superconducting kuenda ku non-superconducting. Kutsamira kwekupisa kweVoc neIsc kwakayerwa pa fixed laser intensity kunoratidzawo polarity reversal pa critical tembiricha pamusoro apo sample inova resistive. Nekutsvaga laser spot kune chikamu chakasiyana che sample, tinoratidza kuti pane electrical potential pane interface, iyo inopa simba rekuparadzanisa ma photo-induced electron-hole pairs. Iyi interface potential inotungamira kubva kuYBCO kuenda ku metal electrode apo YBCO iri superconducting uye inoshandura kuenda kune imwe nzira kana sample yava nonsuperconducting. Kwakatangira simba iri kunogona kunge kwakabatana nemhedzisiro yepedyo pametal-superconductor interface kana YBCO iri superconducting uye inofungidzirwa kuva ~10−8 mV pa50 K nelaser intensity ye502 mW/cm2. Kubata kwechinhu chemhando yep-YBCO pamamiriro akajairika nechinhu chemhando yen-Ag-paste inoumba quasi-pn junction iyo inokonzera maitiro e photovoltaic eYBCO ceramics pakupisa kwakanyanya. Zvataurwa pamusoro apa zvinojekesa mhedzisiro yePV mu high temperature superconducting YBCO ceramics uye zvinovhura nzira yekushandisa mitsva muzvishandiso zve optoelectronic zvakaita se fast passive light detector uye single photon detector.
Kuedza kwe photovoltaic effect kwakaitwa pamuenzaniso weYBCO ceramic une ukobvu hwe 0.52 mm uye chimiro che rectangular che 8.64 × 2.26 mm2 uye kwakavhenekerwa ne continuous wave blue-laser (λ = 450 nm) ine laser spot size ye 1.25 mm mu radius. Kushandisa bulk pane thin film sampuro kunotigonesa kudzidza hunhu hwe photovoltaic hwe superconductor pasina kusangana ne compound yakaoma ye substrate6,7. Uyezve, zvinhu zvakawanda zvinogona kubatsira pakugadzirira kwayo kuri nyore uye mutengo wakaderera. Waya dze copper lead dzakabatana pamuenzaniso weYBCO ne silver paste dzichigadzira ma electrode mana akatenderera angangoita 1 mm mu dhayamita. Daro riri pakati pema electrode maviri e voltage rinenge 5 mm. Hunhu hwe IV hwemuenzaniso hwakayerwa uchishandisa vibration sample magnetometer (VersaLab, Quantum Design) ne quartz crystal window. Standard four-wire method yakashandiswa kuwana ma IV curves. Nzvimbo dze relative dzema electrode nenzvimbo ye laser zvinoratidzwa muFig. 1i.
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Basa iri rakatsigirwa neNational Natural Science Foundation of China (Grant No. 60571063), iyo Fundamental Research Projects yeHenan Province, China (Grant No. 122300410231).
FY akanyora rugwaro rwepepa uye MYH akagadzira sample yeYBCO ceramic. FY naMYH vakaita bvunzo iyi uye vakaongorora mhedzisiro yacho. FGC ndiyo yakatungamira chirongwa ichi uye dudziro yesainzi yedata racho. Vanyori vese vakaongorora gwaro racho.
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Yang, F., Han, M. & Chang, F. Kwakatangira simba remagetsi ezuva (photovoltaic effect) mukugadzira zvinhu zvesimbi zveYBa2Cu3O6.96. Sci Rep 5, 11504 (2015). https://doi.org/10.1038/srep11504
Nekutumira mhinduro unobvuma kutevedzera Mitemo yedu neMitemo yeNharaunda. Kana ukaona chimwe chinhu chisina kunaka kana chisingaenderane nemitemo yedu kana nhungamiro ndapota chiratidze sechisina kukodzera.
Nguva yekutumira: Kubvumbi-22-2020