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Impact of elemental arsenic on electrical characteristics of metal-oxide-semiconductor capacitors on GaAs using atomic-layer deposited HfO2 gate dielectric

2008; American Institute of Physics; Volume: 92; Issue: 24 Linguagem: Inglês

10.1063/1.2949079

1520-8842

Rahul Suri, Daniel J. Lichtenwalner, Veena Misra,

Advanced Memory and Neural Computing

The interface between HfO2 and sulfur-passivated GaAs was analyzed after atomic-layer deposition (ALD) and postdeposition annealing (PDA) using x-ray photoelectron spectroscopy. The HfO2 ALD process resulted in elemental arsenic buildup at the interface. Electrical measurements confirmed that the elemental arsenic caused anomalously large values for equivalent oxide thickness (EOT), hysteresis, and frequency dispersion in accumulation. Arsenic outdiffusion after PDA lowered the EOT but increased the gate leakage. Annealing the (NH4)2S-treated GaAs prior to ALD yielded an EOT of 1.85nm and leakage of 6.6×10−4A∕cm2 at Vg=Vfb−1V. This modified passivation scheme looks promising for achieving a high-quality HfO2∕GaAs interface.