Applied Physics Letters · 2012 · 54 citations · 11 references
EngineeringTransient Photocapacitance SpectroscopyVoltage DeficitSemiconductorsIi-vi SemiconductorPhotoelectric SensorElectronic DevicesMetallic Functional MaterialQuantum MaterialsCharge Carrier TransportMaterials EngineeringMaterials ScienceElectrical EngineeringUrbach EnergiesPhysicsTransient PhotocapacitanceSemiconductor MaterialPhotoelectric MeasurementDefect FormationTransition Metal ChalcogenidesApplied PhysicsCondensed Matter PhysicsLight AbsorptionActive DefectsOptoelectronics
Transient photocapacitance (TPC) spectra were obtained on a series of Cu2ZnSn(Se,S)4 absorber devices with varying Se:S ratios, providing bandgaps (Eg) between 1 eV and 1.5 eV. Efficiencies varied between 8.3% and 9.3% for devices with Eg ≤ 1.2 eV and were near 6.5% for devices with Eg ≥ 1.4 eV. The TPC spectra revealed a band-tail region with Urbach energies at or below 18 meV for the first group, but in the 25-30 meV range for the higher band-gap samples. A deeper defect band centered near 0.8 eV was also observed in most samples. We identified a correlation between the Urbach energies and the voltage deficit in these devices.
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