Surface Passivation and Interface Properties of Bulk GaAs and Epitaxial-GaAs/Ge Using Atomic Layer Deposited TiAlO Alloy Dielectric

Abstract

High quality surface passivation on bulk-GaAs substrates and epitaxial-GaAs/Ge (epi-GaAs) layers were achieved by using atomic layer deposited (ALD) titanium aluminum oxide (TiAlO) alloy dielectric. The TiAlO alloy dielectric suppresses the formation of defective native oxide on GaAs layers. X-ray photoelectron spectroscopy (XPS) analysis shows interfacial arsenic oxide (As(x)O(y)) and elemental arsenic (As) were completely removed from the GaAs surface. Energy dispersive X-ray diffraction (EDX) analysis and secondary ion mass spectroscopy (SIMS) analysis showed that TiAlO dielectric is an effective barrier layer for reducing the out-diffusion of elemental atoms, enhancing the electrical properties of bulk-GaAs based metal-oxide-semiconductor (MOS) devices. Moreover, ALD TiAlO alloy dielectric on epi-GaAs with AlGaAs buffer layer realized smooth interface between epi-GaAs layers and TiAlO dielectric, yielding a high quality surface passivation on epi-GaAs layers, much sought-after for high-speed transistor applications on a silicon platform. Presence of a thin AlGaAs buffer layer between epi-GaAs and Ge substrates improved interface quality and gate dielectric quality through the reduction of interfacial layer formation (Ga(x)O(y)) and suppression of elemental out-diffusion (Ga and As). The AlGaAs buffer layer and TiAlO dielectric play a key role to suppress the roughening, interfacial layer formation, and impurity diffusion into the dielectric, which in turn largely enhances the electrical property of the epi-GaAs MOS devices.

Evidence for Chemicals Intermingling at Silicon/Titanium Oxide (TiOx) Interface and Existence of Multiple Bonding States in Monolithic TiOx

“…Metal oxides (MOs) are widely used as gate dielectrics and surface passivation materials in a number of electronic and optoelectronic devices . The nature of the semiconductor–MO interface and the structural characteristics of the MOs predominantly influence the fundamental properties of these devices . Thus, a greater understanding of the interface and structural properties of MOs is crucial to realize advanced devices.…”

“…Thus, a greater understanding of the interface and structural properties of MOs is crucial to realize advanced devices. Silicon oxide (SiO x ), aluminum oxide (AlO x ), and hafnium oxide (HfO x ) are commonly used MOs in semiconductor materials, including, but not limited to, crystalline silicon (c‐Si) and gallium arsenide (GaAs) . Muller et al have extensively examined the nature of the c‐Si/SiO 2 interface to control a nanometer‐thick gate oxide for advanced electronics.…”

Diffusion of In0.53Ga0.47As elements through hafnium oxide during post deposition annealing

“…15 Decomposed elements from the native oxides could diffuse through the high-k dielectric which would lead to electrical instabilities. 16,17 Most recently, using ex-situ hard X-ray photoelectron spectroscopy (XPS), Weiland et al 18 observed Ga and As out-diffusion on Al 2 O 3 /In 0.53 Ga 0.47 As stacks after N 2 annealing at temperatures between 400 C and 700 C. In another study, Kang et al 19 noted Ga-O formation on the top surface on Al 2 O 3 /HfO 2 /GaAs gate stacks after PDA at 700 C. All these studies suggest that III-V substrate elements might diffuse completely through the high-k dielectric film after post deposition anneals, although there have been no unambiguous proof and quantification of such diffusion. It is therefore important to devise experiments with tools that can provide clear evidence for elemental diffusion and changes in the chemical composition of high-k/III-V gate stacks for future production of high mobility devices.…”

Color tunable low cost transparent heat reflector using copper and titanium oxide for energy saving application

“…Furthermore, they also reported that the thin film of titanium (~5–20 nm) significantly reduced the Cu out-diffusion even at high temperature 56 . In our recent study on alloy oxides, presence of thin film TiO 2 in Al 2 O 3 significantly reduced the elemental out diffusion in gallium-arsenide based devices 57 . For the sputter grown TiO 2 /Cu/TiO 2 structure, from SIMS analysis, it was found that there is a hump of Ti at TiO 2 /Cu interface, reveals formation of the Ti-rich oxide at the Cu/TiO 2 interface.…”