Ultra-high thermal stability and extremely low Dit on HfO2/p-GaAs(001) interface

Abstract

Molecular beam epitaxy (MBE) HfO2 films ~1.5nm thick were directly deposited on freshly grown GaAs(001)-4×6 reconstructed surfaces. The hetero-structure exhibits outstanding thermal stability up to 900°C with excellent capacitance-voltage (C-V) and leakage current density-electric field (J-E) characteristics. We have extracted low interfacial trap densities (Dit's) with minimum value of 1.3×1011 eV−1cm−2 from the measured quasi-static C-V (QSCV) characteristics. The smallest frequency dispersion of the C-Vs for the MBE-HfO2/p-GaAs(001) is ~5.2% at frequency range of 500 to 1MHz and no trap-induced humps were observed in the C-Vs, as measured at 100°C and 150°C. Also, the leakage current density remains low of 10−8(A/cm2) at E<±3 (MV/cm). The key to passivate GaAs in attaining low Dit's and high-temperature thermal stability is to ensure the cleanness of GaAs surface prior to the high-κ deposition.