Thermal Stability of the AlN/a-Si/GaAs MIS Diodes with Different GaAs Surface Stoichiometry

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Abstract
The thermal stability of AlN/a-Si/GaAs MIS diodes with an a-Si interlayer deposited on (a) As-rich, (b) As-dimerstabilized and (c) Ga-stabilized GaAs surfaces was investigated. In n-type diodes, the accumulation-side capacitance of the C-V curve increased drastically by elevating the annealing temperature to above 650°C in (c), while the capacitance decreased rapidly at 600°C in (a) and slowly above 600°C in (b). The p-type diodes exhibited no distinct change in (a) and (b), but degradation occurred in (c) above 650°C. Diffusion of As into the a-Si layer and formation of interfacial free As are suggested to occur, resulting in generation of donor- and acceptor-type levels, respectively.