Formation of etch pits during carbon doping of gallium arsenide with carbon tetrachloride by metalorganic vapor-phase epitaxy

Abstract

Scanning tunneling microscopy was used to examine the effects of carbon tetrachloride concentration and temperature on the morphology of carbon-doped gallium arsenide films grown by metalorganic vapor-phase epitaxy. Deposition was carried out at 505-545°C, a V/III ratio of 75, and IV/III ratios between 0.5 and 5.0. The growth rate declined monotonically with increasing carbon tetrachloride concentration. Step bunching and pinning was observed at a IV/III ratio of approximately 2.5. Increasing this ratio further resulted in the formation of pits ranging from 20 to 50 nm in diameter. These results can be explained by two competing processes that occur at the step edges: ͑1͒ the reaction of chlorine with adsorbed gallium from the group III precursor, and ͑2͒ the reaction of chlorine with gallium arsenide. Both reactions desorb gallium chlorides and reduce the growth rate, but only the latter reaction produces pits.

Site-specific chemistry of gallium arsenide metalorganic chemical vapor deposition

“…The two changes seen in the STM image illustrate the two competing reaction pathways: equation (1), which consumes adsorbed gallium; and equation (2), which etches the gallium arsenide film. The gallium arsenide etching reaction is further manifest in the nano-scale features of the film [16]. Shown in Fig.…”

“…Carbon tetrachloride is an efficient source for p-type carbon doping of gallium arsenide films [16,31]. The surface reactions of this dopant molecule are complex and strongly impact the MOCVD growth process.…”

“…The surface reactions of this dopant molecule are complex and strongly impact the MOCVD growth process. Carbon tetrachloride decomposes on the GaAs (001) surface by two competing pathways [9,13,16]:…”

“…In metalorganic chemical vapor deposition, there is a confluence of several scientific fields, encompassing device physics, materials science, reactor engineering, and surface chemistry [2,3]. It is our opinion that the latter field holds the key to unlocking the full potential of the MOCVD process, and it is this area where we have focussed our energies over the past five years [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]32]. Some of the highlights of this research will be described in the present paper.…”

Desarrollo de células solares de doble unión de GaInP/GaAs para concentraciones luminosas elevadas (Development of GaInP/GaAs dual-junction solar cells for high light concentrations).

“…When the etching rate and growth rate are similar, due to the removal of all the Ga atoms from the growing surface, the surface morphology is degraded by the new arrangement of species on the surface and the material stoichiometry alteration. In [Begarney99], the formation of etch pits is also reported when using CCl 4 at low growth temperatures (< 550 ºC), and high [CCl 4 ] values such that the hole concentration is in the saturated region.…”