Evidence of electron and hole inversion in GaAs metal-oxide-semiconductor capacitors with HfO2 gate dielectrics and α-Si∕SiO2 interlayers

Abstract

Evidence of inversion in GaAs metal-oxide-semiconductor capacitors with $\mathrm{Hf}{\mathrm{O}}_2$ gate dielectrics and $\alpha \text{-}\mathrm{Si}∕\mathrm{Si}{\mathrm{O}}_2$ interlayers is reported. Capacitors formed on $n\text{-}\mathrm{Ga}\mathrm{As}$ with atomic layer-deposited $\mathrm{Hf}{\mathrm{O}}_2$ displayed $C\text{-}V$ characteristics with minimum $D_{\mathrm{it}}$ of $7\times {10}^{11}{\mathrm{cm}}^{-2}∕\mathrm{eV}$ , while capacitors with molecular beam epitaxy-deposited $\mathrm{Hf}{\mathrm{O}}_2$ on $p\text{-}\mathrm{Ga}\mathrm{As}$ had $D_{\mathrm{it}}=3\times {10}^{12}{\mathrm{cm}}^{-2}∕\mathrm{eV}$ . Lateral charge transport was confirmed using illuminated $C\text{-}V$ measurements on capacitors fabricated with thick Al electrodes. Under these conditions, capacitors on $n\text{-}\mathrm{Ga}\mathrm{As}$ $\left(p\text{-}\mathrm{Ga}\mathrm{As}\right)$ showed “low-frequency” $C\text{-}V$ behavior, indicated by a sharp capacitance increase and saturation at negative (positive) gate bias, confirming the presence of mobile charge at the semiconductor/dielectric interface.