Nitridation of GaAs (001) Surface Studied by Auger Electron Spectroscopy

Abstract

Auger electron spectroscopy (AES) has been used to investigate the processes taking place during the initial stages of nitridation of GaAs(001)-2 × 4 surface by active nitrogen species. The results of analysis of the spectral positions of the Auger electron signals from Ga, As and N, as well as their dependencies on the nitrogen exposure show that the processes taking place during nitridation greatly differ depending on the nitridation temperature. At low temperatures (≤200 • C) nitridation is hindered by kinetic restrictions on the atomic migration, leading to the island growth with the formation of the disordered GaAsN phase in the subsurface region. At high temperatures (≥500 • C) the process of nitridation takes place simultaneously with the etching of the surface due to decomposition of the substrate, resulting in the rough interface between the GaN and GaAs phases. However, for intermediate nitridation temperatures (300 • C-400 • C) AES results indicate that one monolayer of N atoms may be formed on the substrate during the initial stage of nitridation. The post-nitridation annealing of the samples nitrided at the intermediate temperatures results in the formation of a crystalline GaN layer, the line shape of the AES signals from which is identical to that for a GaN reference sample.

Chemistry of Wet Treatment of GaAs(111)B and GaAs(111)A in Hydrazine-Sulfide Solutions

“…Among them, N 2 -based ones are most widely used. Due to the stability of the N-N bond in the nitrogen molecules, nitridation can only be produced by excited nitrogen species obtained using plasmas, [3][4][5][6][7][8][9] electron-beams, 10 ions, 11,12 thermal cracking, [13][14][15] photons, 16,17 or catalytically decomposed nitrogen molecules. 18 Other nitridation treatments use plasma-activated or thermoactivated NH 3 ͑Refs.…”

“…26 However, treatments using activated nitrogen species are not ideal for the semiconductor nitridation. Although significant improvements have been made by optimizing the plasma reactivity 27 and the substrate temperature, 4,9,11 a relatively thick layer of nitride is generally formed, for which the thickness saturates at values larger than several nanometers. 3,5 Therefore, because of the high GaAs/GaN lattice mismatch ͑ϳ20%͒, such nitride films include voids, mismatch defects, and arsenic atoms.…”

Properties of cubic GaN films obtained by nitridation of porous GaAs(001)

“…Thus, the atoms of nitrogen (due to the small covalent radius 0.07 nm) during the nitridation process penetrate into the bulk of GaAs and substitute the As atoms. This can be explained by the large difference in binding energy Ga-N (4.2 eV) and Ga-As (2 eV), and consequently, As atoms are widely replaced by N atoms on the surface, forming the Ga-N bonds [11].…”

Nitridation of porous GaAs by an ECR ammonia plasma

“…High-performance GaN-based devices have been fabricated, including violet, blue and blue-green light-emitting diodes (LEDs) [5,6], as well as high frequency, high temperature transistors [7]. Although there are many reports [8][9][10][11] of synthesizing thin films of GaN by exposing the surface of GaAs to nitrogen ions generated by different plasma resources, a lot of research still needs to be carried out to understand the actual mechanism of the nitriding process, the effect of plasma parameters on the quality of the nitrided films and the effect of pre-treatment of GaAs surface, such as chemical and dry etching.…”