Reflectance‐difference spectroscopy study of surface reactions in atomic layer epitaxy of GaAs using trimethylgallium and tertiarybutylarsine

1991 ◽  
Vol 58 (20) ◽  
pp. 2261-2263 ◽  
Author(s):  
B. Y. Maa ◽  
P. D. Dapkus
Keyword(s):  
Surface Reactions ◽  
Atomic Layer ◽  
Atomic Layer Epitaxy ◽  
Difference Spectroscopy ◽  
Spectroscopy Study ◽  
Reflectance Difference Spectroscopy

Determination of growth parameters for atomic layer epitaxy using reflectance difference spectroscopy

1996 ◽  
Vol 74 (S1) ◽  
pp. 85-88 ◽  
Author(s):  
R. Arès ◽  
C. A. Tran ◽  
S. P. Watkins
Keyword(s):  
Growth Rate ◽  
Growth Parameters ◽  
Atomic Layer ◽  
Atomic Layer Epitaxy ◽  
Gas Flows ◽  
Difference Spectroscopy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Reflectance Difference Spectroscopy

Reflectance difference spectroscopy (RDS) has been used to monitor the anisotropy of the surface of InAs and GaAs grown by atomic layer epitaxy (ALE). Saturation of the RDS signal is observed when the surface is fully covered with one monolayer of the impinging surface species. This property is used to optimize the growth interruptions for the ALE cycle. Good correlation of the RDS saturation is observed with growth-rate measurements obtained by X-ray diffraction (XRD). When exposure times are sufficiently long for saturation to be observed in the RDS signal, a growth rate of one monolayer per cycle (1 ML/cycle) is achieved. In principle all the different growth parameters such as exposure and purge times as well as gas flows can be determined in a few cycles performed on a single substrate. Without RDS the same results would require several growth runs and time consuming X-ray characterization.

Surface reconstruction of GaAs (001) during OMCVD growth

1993 ◽  
Vol 344 (1673) ◽  
pp. 443-452 ◽  
Keyword(s):  
Surface Reconstruction ◽  
Atmospheric Pressure ◽  
Molecular Beam ◽  
Vapour Deposition ◽  
Chemical Vapour ◽  
Atomic Layer ◽  
Atomic Layer Epitaxy ◽  
Difference Spectroscopy ◽  
Reflectance Difference Spectroscopy ◽  
Surface Reconstructions

Surface reconstruction of GaAs (001) during organometallic chemical vapour deposition (OMCVD) growth has been investigated with reflectance-difference spectroscopy (RDS). RD spectra reveal that surface reconstructions similar or identical to (4 x 2), (2 x 4), and c (4 x 4) that occur on surface prepared by molecular beam epitaxy (MBE) in ultrahigh vacuum (UHV) occur even in atmospheric pressure OMCVD growth environments. Based on the RDS database we established on static surfaces in UHV , we studied the structure of surfaces under both static and dynamic conditions in non-UHV ambients. We find, in contrast to previous models, that the surfaces under various non-UHV conditions exhibit dimer formation. In addition, OMCVD growth and atomic layer epitaxy (ALE) typically occur under disordered c (4 x 4)[ d (4 x 4)]-like conditions where the surface is terminated by multilayers of As. When trimethylgallium (TMG) and arsine (AsH 3 ) are supplied simultaneously, the surface structure varies as a function of the supply rates of TMG and AsH 3 , and the substrate temperature.

Reflectance difference spectroscopy study of Ag growth on W(110)

2006 ◽  
Vol 600 (20) ◽  
pp. L281-L285 ◽  
Author(s):  
L.D. Sun ◽  
M. Hohage ◽  
P. Zeppenfeld ◽  
C. Deisl ◽  
E. Bertel
Keyword(s):  
Difference Spectroscopy ◽  
Spectroscopy Study ◽  
Reflectance Difference Spectroscopy

The Mechanisms and Kinetics of Surface Reactions of Trimethylgallium on GaAs (001) Surfaces and Its Relevance to Atomic Layer Epitaxy

1991 ◽  
Vol 222 ◽  
Author(s):  
B. Y. Maa ◽  
P. D. Dapkus
Keyword(s):  
Photoelectron Spectroscopy ◽  
Selective Adsorption ◽  
Surface Reactions ◽  
Optimal Strategies ◽  
Atomic Layer ◽  
High Energy ◽  
Reflectance Difference Spectroscopy ◽  
Reconstructed Surfaces ◽  
Surface Reaction Kinetics ◽  
Kinetics Of

ABSTRACTX-ray photoelectron spectroscopy (XPS) and reflection high energy electron diffraction (RHEED) have been applied to study the stable adsorbed Ga species and surface structures after GaAs (001) 2 × 4 As-rich surfaces are exposed to TMGa. These studies show that Ga atoms are the final adsorbed species, that Ga deposition is saturated at one atomic layer at temperatures between 360 and 530 °C and that the surface converts from a 2 × 4 to a 4 × 6 reconstruction after TMGa adsorption. To understand the surface reaction kinetics involved, reflectance-difference spectroscopy (RDS), an in situ rea-ltime optical technique developed by Aspnes et al., is applied to investigate TMGa adsorption on (001) GaAs surfaces. The kinetics of the surface reactions and reconstructions have been characterized over the temperature range from 400 to 500 °C using RDS. The transient RDS behaviors are interpreted by the application of a model that involves selective adsorption and reaction of TMGa at surface As sites and at Ga vacancies on Ga-rich reconstructed surfaces. Based upon these interpretations, rates of reaction and by product desorption are determined that suggest optimal strategies for ALE growth of GaAs.

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