Decreasing Defect‐State Density of Al₂O₃/Ga_xIn_1−xAs Device Interfaces with InO_x Structures

Abstract

Control of defect densities at insulator/GaxIn1−xAs interfaces is essential for optimal operation of various devices like transistors and infrared detectors to suppress, for example, nonradiative recombination, Fermi‐level pinning, and leakage currents. It is reported that a thin InOx interface layer is useful to limit the formation of these defects by showing effect of InOx on quantum efficiency of Ga0.45In0.55As detector and on photoluminescence of GaAs. A study of the Al2O3/GaAs interface via hard X‐ray synchrotron photoelectron spectroscopy reveals chemical structure changes at the interface induced by this beneficial InOx incorporation: the InOx sheet acts as an O diffusion barrier that prevents oxidation of GaAs and concomitant As bond rupture.

Oxidation-Induced Changes in the ALD-Al2O3/InAs(100) Interface and Control of the Changes for Device Processing

“…29 However, sources of defect levels can remain if thermally stable In 2 O 3 and Ga 2 O 3 oxide phases stay at the interface. 27,30 Recently, D it of the same order was obtained also by Babadi et al with hydrofluoric acid (HF) etching and alternating cycles of nitrogen plasma and trimethyl aluminum (TMA) before depositing HfO 2 or ZrO 2 dielectric films on InAs(100). 31 deposition annealing at 500 ºC in forming gas.…”

“…Moreover, the interface defect states lead to undesirable non-radiative recombination of charge carriers resulting in energy losses and degraded operation performance. [25][26][27] Defects are often the starting point for further electrical failure and oxide breakdown in general. In the aim of reducing D it , it is important to investigate and modify the interface chemistry on an atomic scale.…”

“…We have investigated an alternative technique to control oxide/III-V interface quality. 27,34 In contrast to the common target of avoiding (or minimizing) the oxidation of semiconductor surfaces, we have performed intentional pre-oxidations of semiconductor surfaces in a controlled manner prior to growing the insulator film. Through this method, a clean III-V surface is pre-oxidized in an ultra-high vacuum (UHV) chamber using the parameters that result in a crystalline oxidized layer and limits the effects of subsequent, random oxidation routes in air or during the ALD growth.…”

“…30,35 Among the various interfaces. 27,30,[35][36][37][38][39] For example, D it of 10 11 cm -2 eV -1 was obtained in a metal-oxidesemiconductor capacitor if InAs(100)(3×1)-O was used before low temperature ALD-HfO 2 growth. 36 In addition, the photoluminescence intensity of an Al 2 O 3 /GaAs(100) interface doubled, a direct indication of decreased interface-defect density, when an In deposition and c(4×2)-O treatment was carried out.…”

“…38 Later, use of this approach provided also a clear increase in quantum efficiency of an infrared photodetector. 27 41 and why the improvement in device performance remains after the ALD growth. 27,36,37 The extended crystalline oxide layer of InAs would be also consistent with previous high-resolution photoemission measurements from the surface.…”