Study of the Deep Levels of a GaAs/p-GaAs 1-x Bi x Heterostructure Grown by Molecular Beam Epitaxy
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Study of the Deep Levels of a GaAs/p-GaAs1xBix Heterostructure Grown by Molecular Beam Epitaxy Takuma Fuyuki1, Shota Kashiyama1, Kunishige Oe1, and Masahiro Yoshimoto1 Department of Electronics, Kyoto Institute of Technology, Sakyo, Kyoto, 606-8585, Japan
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ABSTRACT Deep-level densities of p-GaAs1xBix and at the GaAs/p-GaAs1xBix heterointerface have been shown to be sufficiently low for device applications based on the results of deep-level transient spectroscopy, isothermal capacitance transient spectroscopy and admittance spectroscopy. Although the metastable alloy of GaAs1xBix is grown by molecular beam epitaxy at low temperature (370 °C), the deep-level density of p-GaAs1xBix is suppressed such that it is on the order of 1015 cm3. The state density at the heterointerface was determined to be 8 u 1011 cm2eV−1, which is comparable to other III–V heterointerfaces formed at high temperatures. The surfactant-like effect of Bi is believed to prevent defect formation during low-temperature growth. INTRODUCTION Bismuth (Bi)-containing III-V alloys such as GaAs1-xBix with semimetallic GaBi have recently been investigated for a number of potential device applications. Incorporation of a small amount of Bi atoms into GaAs causes a large reduction in the band gap energy (Eg) [1-4]; the reduction ratio of Eg because of Bi incorporation is six and three times greater than what is achievable through the incorporation of indium and antimony, respectively [5]. It has been proposed that Bi-containing III-V alloys have anomalous temperature-insensitive band gaps [6,7]. These unusual properties open up the possibility of long-wavelength optoelectronics [8], photovoltaics, and spintronics. Because Bi-containing III-V alloys are metastable, low-temperature growth (
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