Epitaxy of GaAs by the Close‐Spaced Vapor Transport Technique

Abstract

Thin epitaxial normalGaAs films have been grown on (100) semi‐insulating normalGaAs (SI normalGaAs ) by close‐spaced vapor transport (CSVT). The epitaxy has been confirmed by x‐ray diffraction spectra and SEM observation of etch pit shapes and orientations. The effect of hydrogen flux, water vapor pressure, distance between the source and the substrate, and transport temperature on the film growth has been measured and analyzed. A model based on the variation of the equilibrium constants of the reactions occurring at the surface of the source and the substrate has been developed to elucidate the growth of normalGaAs . The measurements of transport properties, performed on the CSVT depositions, show that the deposited normalGaAs films are always n‐type independently of the used source (n‐type, p‐type, or SI normalGaAs ). The unintentionally introduced dopant concentration may vary from 5×1016 normalto 2×1018 cm−3 . It is shown that shallow traps associated to EL2 deep levels can be responsible for part of this doping, on the lowest charge carrier density side, but not above ∼5×1017 cm−3 . An unwanted dopant is always introduced by the present technique. It is proposed that Si could be the unwanted doping agent.

Electronic GaAs-on-Silicon Material for Advanced High-Speed Optoelectronic Devices

“…For the case of GaAs homoepitaxy, this functional dependence of growth rate on parameters TI, T 2 , d, and x has been verified [50].…”

“…According to the model of Cote et al [50,51], the CSVT growth rate is determined by the flux J of Ga 2 0 molecules incident on the seed surface. This flux originates from the concentration gradient resulting from the relatively high partial pressure of Ga 2 0 at the source wafer and the lower partial pressure of Ga 2 0 at the seed.…”

A low temperature photoluminescence study of CSVT grown GaAs epitaxial layers

“…This was the "great" starting period of vapour phase technologies. The second era for CSVT was the second half of the eighties, and the beginning of the nineties [6,7].By that time the vapour phase epitaxy techniques based on halogen transport became widespread and the method based on metal-organic precursors was developed for binary and ternary III-V compounds. Nevertheless CSVT still remained an attractive technology.…”

“…The possibility to grow semi-insulating (SI) or nearly SI GaAs with controlled EL2 concentration gave a great impact to the use of CSVT [8,9]. Preparation of photovoltaic structures, especially GaAs on Ge heterostructures, was the other dominant direction of CSVT applications [6,10].The second revival, the third era is the present time, when the solar-energy conversion is the main aim. CSVT has been applied to III -Vs, like GaAs on Si, InGaP on GaAs, even combined with LPE method [11,12].…”