Controlling conduction band alignment and carrier concentration in gallium-doped magnesium zinc oxide by reactive cosputtering

Abstract

Gallium-doped magnesium zinc oxide (GMZO) holds promise as a UV transparent conducting oxide with tunable bandgap and conductivity, though there has been relatively limited exploration of the broad compositional space available. Conductive GMZO films were deposited by reactive cosputtering at room temperature followed by annealing. The contributions of alloying and the Burstein–Moss effect to the optical bandgap were decoupled through comparisons of as-deposited and annealed films. Compositional analysis in conjunction with electrical characterization was used to quantify the activation of Ga doping in MZO. Combinatorial synthesis was used to explore the optoelectronic performance over a broad composition space. Reactive cosputtering can be used to tailor GMZO properties for optoelectronic applications over a wide range of bandgaps (3.3–4 eV) and resistivity (10−3–>100 Ω cm) through appropriate control of the Mg/Zn ratio and Ga content, respectively.

Thermomechanical Cleave of Polycrystalline CdTe Solar Cells and its Applications: A Review

“…For example, Ga‐doped MgZnO shows promise as an n‐type junction partner in group V‐doped devices as it has tunable CBO (−0.2 to 0.5 eV) and electron density (≈10 19 –4 × 10 20 cm −3 ) but requires a 500 °C vacuum activation anneal. [ 111 ] Another consideration is the deposition ambient of the reconstructed emitter or passivating material as it can alter the chemistry at the front interface. For example, reactive sputtering may oxidize the CdSe x Te 1− x surface, which could provide beneficial passivation of chalcogenides on the one hand or form compensating defects that reduce V OC on the other.…”

Revealing the Importance of Front Interface Quality in Highly Doped CdSexTe1–x Solar Cells

“…Using C–V , dual-wavelength TRPL, and QE, this difference was attributed to increased recombination at the front interface as well as heightened sensitivity to it. In future work, sensitivity to the front interface may be reduced by improving the junction field, such as through increased emitter doping (e.g., with Ga-doped MZO , or SnO 2 ) and/or addressing dopant compensation in the absorber, which may be of particular concern at heterointerfaces (e.g., the front interface). However, highly doped CdSeTe:As devices are inherently more sensitive to front interface effects due to their collapsed depletion region, suggesting that chemical passivation of the front interface may be of particular importance.…”