Structural, electrical and photovoltaic characteristics of n- ZnSe/p-Ge heterojunctions

摘要

Ahighqualityn-ZnSe/p-GeheterojunctionisproducedbyMetalorganicchemicalvapordeposition(MOCVD)nbsp;nbsp;technique.Thenbsp;devicesnbsp;nbsp;structurenbsp;nbsp;werenbsp;nbsp;investigatedbyX-raydiffractionandscanningelectronmicroscopy.Thedeviceshavegoodreproducibilityoftheirelectricalcharacteristicsandhighrectificationratio.Theelectricalnbsp;andnbsp;photovoltaicnbsp;propertiesnbsp;ofn-ZnSe/p-Genbsp;heterojunctionnbsp;werenbsp;investigatednbsp;bymeasuringnbsp;currentdensity-voltagenbsp;(J-V)nbsp;andcapacitance-voltagenbsp;(C-V)nbsp;characteristicsnbsp;atvariousnbsp;temperaturesandunderlightilluminationof80mW/cm2.nbsp;Theanalysisofdarknbsp;nbsp;current-voltagecharacteristicsinthetemperaturerange300-400Kwerepresentedinordertoelucidatetheconductionmechanismsandtoevaluatethedeviceparameters.ThechargetransportconductionmechanismintheforwardbiasedconditioninthelowvoltageregionisdescribedbythemodifiedSchockleyeffect.Forhighbiases,Vge;0.6V,thedarkcurrentnbsp;isaspacechargelimitedcurrent(SCLC)controlledbyasingledominanttraplevel.Thecapacitanceofthedevicewasmeasuredasafunctionofappliedvoltageatafrequencyof1MHz,attemperaturesrangingfrom300to400K,indicatingtheformationofp-njunctionbetweenZnSeandGeandthebuilt-inpotentialwasfoundtodecreasewiththeincreaseintemperature.Thenbsp;photovoltaiccharacteristicsofthedevicebasedonanefficientdonor/acceptorcombinationofn-ZnSe/p-Genbsp;heterojunctionswerealsostudied.