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Properties of Arsenic–Doped ZnTe Thin Films as a Back Contact for CdTe Solar Cells
摘要： As-doped polycrystalline ZnTe layers grown by metalorganic chemical vapor deposition (MOCVD) have been investigated as a back contact for CdTe solar cells. While undoped ZnTe ?lms were essentially insulating, the doped layers showed signi?cant rise in conductivity with increasing As concentration. High p-type carrier densities up 4.5 × 1018 cm?3 was measured by the Hall-e?ect in heavily doped ZnTe:As ?lms, displaying electrical properties comparable to epitaxial ZnTe single crystalline thin ?lms in the literature. Device incorporation with as-deposited ZnTe:As yielded lower photovoltaic (PV) performance compared to reference devices, due to losses in the open-circuit potential (VOC) and ?ll factor (FF) related to reducing p-type doping density (NA) in the absorber layer. Some minor recovery observed in absorber doping following a Cl-free post–ZnTe:As deposition anneal in hydrogen at 420 ?C contributed to a slight improvement in VOC and NA, highlighting the signi?cance of back contact activation. A mild CdCl2 activation process on the ZnTe:As back contact layer via a sacri?cial CdS cap layer has been assessed to suppress Zn losses, which occur in the case of standard CdCl2 anneal treatments (CHT) via formation of volatile ZnCl2. The CdS sacri?cial cap was e?ective in minimising the Zn loss. Compared to untreated and non-capped, mild CHT processed ZnTe:As back contacted devices, mild CHT with a CdS barrier showed the highest recovery in absorber doping and an ~10 mV gain in VOC, with the best cell e?ciency approaching the baseline devices.
关键词： solar cells,CdTe,metalorganic chemical vapor deposition (MOCVD),ZnTe:As back contact,thin ?lms
更新于2025-09-11 14:15:04
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Thermal Annealing Effects on the Electrical and Structural Properties of Ni/Pt Schottky Contacts on the Quaternary AlInGaN Epilayer
摘要： Pt/Au, Ni/Au, Ni/Pt/Au Schottky contacts were placed on a quaternary Al0.84In0.13Ga0.03N epilayer. The electrical and structural properties of the as-deposited Pt/Au, Ni/Au, Ni/Pt/Au and annealed Ni/Pt/Au Schottky contacts were investigated as a function of annealing temperature using current–voltage (I–V), capacitance–voltage (C–V), and high resolution x-ray diffraction measurements (HR-XRD). According to the I–V, Norde, and C–V methods, the highest Schottky barrier height (SBH) was obtained for the Pt/Au (0.82 eV (I–V), 0.83 eV (Norde), and 1.09 eV (C–V)) contacts when they were compared with the other as-deposited Schottky contacts. The estimated SBH of the annealed Ni/Pt/Au Schottky contacts, calculated from the I–V results, were 0.80 eV, 0.79 eV, and 0.78 eV at 300°C, 400°C, and 500°C, respectively. The SBH decreases with an increase in the annealing temperature up to 500°C compared with that of the as-deposited Ni/Pt/Au Schottky contact. The observed extra peaks in the annealed samples confirm the formation of a new interfacial phase at the interface. However, the diffraction patterns of the annealed Schottky contacts did not change as a function of the annealing temperature. The higher ideality factors values were obtained for as-deposited Pt/Au (5.69), Ni/Au (6.09), and Ni/Pt/Au (6.42) Schottky contacts and annealed Ni/Pt/Au (6.42) Schottky contacts at 300°C (6.89), 400°C (7.43), and 500°C (8.04). The higher n results can be attributed to current-transport mechanisms other than thermionic emission, such as dislocation related tunneling.
关键词： A3. metalorganic chemical vapor deposition (MOCVD),annealing effects,A1. Schottky,B1. AlInGaN
更新于2025-09-10 09:29:36