Site-specific chemistry of gallium arsenide metalorganic chemical vapor deposition

Abstract

Herein, we summarize our studies of the surface chemistry of gallium arsenide as it pertains to the metalorganic chemical-vapor deposition of compound semiconductors. It has been found by scanning tunneling microscopy and vibrational spectroscopy that the adsorption of reactant molecules on reconstructed GaAs (001) surfaces is "site-specific." Trimethylgallium dissociatively adsorbs only on arsenic sites, whereas arsine dissociatively adsorbs only on gallium sites. The decomposition of one precursor molecule (Ga(CH 3) 3 or AsH 3) creates the site for the decomposition of the other molecule (AsH 3 or Ga(CH 3) 3 , respectively). In this fashion, the crystal grows one atomic layer at a time. Studies of carbon doping with carbon tetrachloride have shown that adsorbed chlorine attacks the exposed gallium and generates volatile GaCl x species. The sitespecific nature of this reaction leads to a dramatic change in the film morphology, with the formation of 30nm etch pits randomly distributed over the surface.

Mechanism of Arsine Adsorption on the Gallium-Rich GaAs(001)−(4 × 2) Surface

“…The film surface plays a crucial role in this process, because it mediates the decomposition of the group III and group V reagents. [4][5][6][7][8][9][10][11][12][13] It is essential to understand the heterogeneous decomposition reactions because they affect the growth rate, film composition, film morphology, and dopant profiles, all of which impact device performance.…”

Reflection Absorption IR Spectroscopy (RAIRS)

“…However, the edges of samples must fi rst be beveled in order to couple the radiation in and out. This method was fi rst applied to investigations of the morphology of H -terminated Si surfaces upon etching [21] , and also of the surface chemistry of metalorganic chemical vapor deposition ( MOCVD ), which is the technique of choice when fabricating Group III/V compound semiconductor devices [23] . When using the SEIRA effect, the fi lms to be analyzed are typically deposited on metallic island substrates, or vice versa.…”

A computational study of gas-phase and surface reactions in deposition and etching of GaAs and AlAs in the presence of HCl

“…As a result, the mechanism of growth from Ga(CH 3 ) 3 and AsH 3 is now largely understood [11][12][13][14]. At conventional growth temperatures (800-1000 C) the GaAs surface exhibits As-rich c(4 Â 4) reconstruction [15].…”