Diagnostics of Gas Reaction Using Trimethylgallium-AsH₃ and Triethylgallium-AsH₃ in Low-Pressure Organometallic Vapor Phase Epitaxy

Abstract

The dominant gas species produced in low-pressure organometallic vapor phase epitaxy (OMVPE) using trimethylgallium (TMG)-arsine (AsH3) and triethylgallium (TEG)-AsH3 systems have been studied with a quadrupole mass spectrometer. The gas species markedly depended on the growth pressure, which varied from 0.05 to 100 Torr. At pressures below 1 Torr, alkylarsines increased markedly with decreasing pressure. The dominant hydrocarbon species were CH4 in the TMG-AsH3 system and C2H4, C2H6 and C3H8 in the TEG-AsH3 system. In the TMG-AsH3 system, the CH4 concentration decreased with decreasing pressure below 1 Torr. In the TEG-AsH3 system, however, the species of the dominant hydrocarbons changed with pressure. A detailed analysis shows that CH3 radicals increase below 1 Torr, in good agreement with the increased carbon incorporation in OMVPE GaAs layers grown below 1 Torr.

Impact of CBr4, V/III ratio, temperature and AsH3 concentration on MOVPE growth of GaAsSb:C

“…This behavior is attributed to heterogeneous reactions between AsH x and CBr y species, which result in a C removal from the crystal surface through the formation of As-CBr y or (CH 3 ) n AsH 3Àn complexes. Similar behaviors have also been reported for GaAs [10,26].…”

“…Tateno et al suggested for MOVPE-grown GaAs and AlAs doped with CBr 4 , that CBr y directly reacts with AsH 3 producing As-CBr y [10]. Horiguchi et al, detected methylarsines (CH 3 ) n AsH 3Àn (n=1, 2 and 3) in low-pressure MOVPE growth of GaAs from TMGa and AsH 3 [26]. However, at pressures larger than 1 Torr, the concentration of methylarsines decreased significantly.…”

In situ study of GaAs growth mechanisms using tri-methyl gallium and tri-ethyl gallium precursors in metal-organic vapour phase epitaxy

“…The temperature of 50% decomposition is about 300 C [4,5,8,9] which is much lower than typical growth temperatures. Thus, only very little carbon reaches the surface during growth.…”

“…Using helium or nitrogen instead, the decomposition temperature is 20-30 C higher [4][5][6]. Thus, using TMGa many methyl groups are present on the surface during growth, especially at lower temperatures.…”

The study of carbon incorporation during growth in epitaxial indium antimonide layers prepared by metalorganic magnetron sputtering

“…High background levels of carbon have also been observed in GaAs layers deposited by MOMBE using TMG and arsine (13) or elemental arsenic (14). In these layers, p-type conduction was observed with canier concentrations as high as lo2' cmP3.…”