Kinetics of carbon tetrachloride decomposition during the metalorganic vapor-phase epitaxy of gallium arsenide and indium arsenide

Journal of Applied Physics

et al. 2000

The surface roughness of gallium arsenide ͑001͒ films produced by metalorganic vapor-phase epitaxy has been studied as a function of temperature and growth rate by in situ scanning tunneling microscopy. Height-height correlation analysis reveals that the root-mean-height difference follows a power-law dependence on lateral separation, i.e., ⌫(L)ϭkL a , up to a critical distance L c , after which it remains constant. For layer-by-layer growth, the roughness exponent, ␣, equals 0.25 Ϯ0.05, whereas the critical distance increases from 50 to 150 nm as the substrate temperature increases from 825 to 900 K. The roughness exponent jumps to 0.65Ϯ0.1 upon transitioning to three-dimensional island growth. By relating the height-height correlation analysis to the Einstein diffusivity relationship, the activation energy for gallium surface diffusion has been estimated: E d ϭ1.35Ϯ0.1 eV.

Section: Experimental Methodsmentioning

confidence: 99%

Analysis of the growth modes for gallium arsenide metalorganic vapor-phase epitaxy

Law

Journal of Applied Physics

et al. 2000

“…In a previous study, we showed that reaction ͑1͒ removes adsorbed gallium and accounts for most of the reduction in growth rate, while reaction ͑2͒ causes film etching, and occurs only above a threshold CCl 4 concentration. 19 Pit formation is clearly a consequence of the latter etching reaction. Presented in Fig.…”

Section: Discussionmentioning

confidence: 95%

“…However, little has been reported on the effects of these parameters on film morphology. For example, Hanna et al 3 observed crosshatching in layers 2 to 3 m thick with carbon levels above 8ϫ10 19 cm Ϫ3 . On the other hand, Yang et al 4 reported mirror-like morphologies in films having carbon levels as high as 1ϫ10 20 cm Ϫ3 .…”

Section: Introductionmentioning

confidence: 99%

“…We have investigated the kinetics of CCl 4 decomposition during the MOVPE of GaAs and InAs. 19 It was found that adsorbed chlorine either reacts with adsorbed gallium atoms from the precursor, forming GaCl, or etches the GaAs film, forming GaCl 3 . The surface morphology should be affected in dramatically different ways depending on which of these two reactions occurs.…”

Section: Introductionmentioning

confidence: 99%

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

Journal of Applied Physics

Han

et al. 1999

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.

“…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.…”

Section: Introductionmentioning

confidence: 99%

Site-specific chemistry of gallium arsenide metalorganic chemical vapor deposition

et al. 1999

J. Phys. IV France

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.