Defect studies in low-temperature-grown GaAs

Thesis/Dissertation · Sun Nov 01 00:00:00 EST 1992

DOI:https://doi.org/10.2172/10140831· OSTI ID:10140831

Bliss, David Emory ^[1]

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1. Univ. of California, Berkeley, CA (United States)

High content of excess As is incorporated in GaAs grown by low-temperature molecular-beam-epitaxy (LTMBE). The excess As exists primarily as As antisite defects AsGa and a lesser extent of gallium vacancies V_Ga. The neutral AsGa-related defects were measured by infrared absorption at 1μm. Gallium vacancies, V_Ga, was investigated by slow positron annihilation. Dependence of defect contents on doping was studied by Si and Be dopants. No free carriers are generated by n-type or p-type doping up to 10¹⁹ cm^-3 Si or Be. Raman data indicate Be occupies Ga substitutional sites but Si atom is not substitutional. Si induces more As_Ga in the layer. As As_Ga increases, photoquenchable As_Ga decreases. Fraction of photoquenchable defects correlates to defects within 3 nearest neighbor separations disrupting the metastability. Annealing reduces neutral As_Ga content around 500C, similar to irradiation damaged and plastically deformed Ga_As, as opposed to bulk grown GaAs in which As_Ga-related defects are stable up to 1100C. The lower temperature defect removal is due to V_Ga enhanced diffusion of As_Ga to As precipitates. The supersaturated V_Ga and also decreases during annealing. Annealing kinetics for As_Ga-related defects gives 2.0 ± 0.3 eV and 1.5 ± 0.3 eV migration enthalpies for the As_Ga and V_Ga. This represents the difference between Ga and As atoms hopping into the vacancy. The non-photoquenchable As_Ga-related defects anneal with an activation energy of 1.1 ± 0.3eV. Be acceptors can be activated by 800C annealing. Temperature difference between defect annealing and Be activation formation of As_Ga-Be_Ga pairs. Si donors can only be partially activated.

• Research Organization: Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 10140831
• Report Number(s): LBL-33378; ON: DE93010405
• Resource Relation: Other Information: TH: Thesis (Ph.D.); PBD: Nov 1992
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
GALLIUM ARSENIDES
CRYSTAL DEFECTS
MOLECULAR BEAM EPITAXY
DOPED MATERIALS
BERYLLIUM ADDITIONS
SILICON ADDITIONS
ANNEALING
POSITRONS
360602
STRUCTURE AND PHASE STUDIES