Electrical properties of GaAs metal–oxide–semiconductor structure comprising Al2O3 gate oxide and AlN passivation layer fabricated in situ using a metal–organic vapor deposition/atomic layer deposition hybrid system

Abstract

This paper presents a compressive study on the fabrication and optimization of GaAs metal–oxide–semiconductor (MOS) structures comprising a Al2O3 gate oxide, deposited via atomic layer deposition (ALD), with an AlN interfacial passivation layer prepared in situ via metal–organic chemical vapor deposition (MOCVD). The established protocol afforded self-limiting growth of Al2O3 in the atmospheric MOCVD reactor. Consequently, this enabled successive growth of MOCVD-formed AlN and ALD-formed Al2O3 layers on the GaAs substrate. The effects of AlN thickness, post-deposition anneal (PDA) conditions, and crystal orientation of the GaAs substrate on the electrical properties of the resulting MOS capacitors were investigated. Thin AlN passivation layers afforded incorporation of optimum amounts of nitrogen, leading to good capacitance–voltage (C–V) characteristics with reduced frequency dispersion. In contrast, excessively thick AlN passivation layers degraded the interface, thereby increasing the interfacial density of states (Dit) near the midgap and reducing the conduction band offset. To further improve the interface with the thin AlN passivation layers, the PDA conditions were optimized. Using wet nitrogen at 600 °C was effective to reduce Dit to below 2 × 1012 cm−2 eV−1. Using a (111)A substrate was also effective in reducing the frequency dispersion of accumulation capacitance, thus suggesting the suppression of traps in GaAs located near the dielectric/GaAs interface. The current findings suggest that using an atmosphere ALD process with in situ AlN passivation using the current MOCVD system could be an efficient solution to improving GaAs MOS interfaces.

Effect of an inserted Al2O3 passivation layer for atomic layer deposited HfO2 on indium phosphide

“…A similar phenomenon has also been observed in previous reports [14,18,30]. It can be clearly seen that frequency dispersion occurred in all the InP MOSCAPs, as shown in figure 2(a), as was often found on a compound substrate [20,21]. The amount of frequency dispersion was defined as the percentage ratio of the change in maximum capacitance (C max ) measured from 1 kHz to 1 MHz [12].…”

Interfacial and electrical properties of nanolaminated HfO2/Al2O3 dielectrics on GaN with an AlN interlayer

“…In addition, the significant frequency dispersion in the accumulation region was observed for the single bilayer. The presence of a disordered or defective interfacial region were considered as the origin of accumulation dispersion [18]. At high frequencies, the trapped electrons hardly respond to the ac signal and hence do not contribute to the current flow, increasing the series resistance and decreasing the capacitance [19].…”

Фазовый состав, морфология, оптические и электронные характеристики наноразмерных пленок AlN, выращенных на подложках GaAs(100) с разориентацией

“…Важной особенностью нитрида алюминия является его прекрасная совместимость с соединениями A III B V , ко-торые используются в качестве подложки [5,11]. Все это делает AlN одним из важных материалов, легко и успешно встраиваемых в технологические процессы производства компонент оптоэлектроники и солнечной энергетики [12].…”