MOCVD Growth of InAlAsSb Layer for High-Breakdown Voltage HEMT Applications
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Z4.3.1
MOCVD Growth of InAlAsSb Layer for High-Breakdown Voltage HEMT Applications Haruki Yokoyama, Hiroki Sugiyama, Yasuhiro Oda, Michio Sato, Noriyuki Watanabe1 and Takashi Kobayashi NTT Photonics Laboratories, 3-1 Morinosato Wakamiya, Atsugi-shi, Kanagawa, 243-0124 Japan 1 NTT Advanced Technology Corporation, 3-1 Morinosato Wakamiya, Atsugi-shi, Kanagawa, 243-0124 Japan
ABSTRACT This paper studies the decomposition characteristic of group-III sources during InAlAsSb growth on InP substrates by metalorganic chemical vapor deposition (MOCVD) using trimethylindium (TMI), trimethylaluminum (TMA), trimethylantimony (TMSb) and arsine (AsH3). A composition analysis of InAlAsSb layers shows that the group-III compositions in the InAlAsSb layer change remarkably when the flow rate of the group-V source is varied. To clarify the reason for this phenomenon, the growth rates of InAsSb and AlAsSb component are examined. Their changes indicate that TMSb suppresses the decomposition of TMA while AsH3 enhances it. Moreover, the HEMT structure with InP/InAlAsSb Schottky barrier layer, whose InP layer acts as a recess-etch-stop layer, is fabricated for the first time. The I-V characteristics of a fabricated Schottky barrier diode indicate that the reverse leakage current of InP/InAlAsSb is about one order of magnitude smaller than that of commonly used InP/InAlAs.
INTRODUCTION InAlAsSb quaternary alloy, which offers a large energy band gap[1] and large Schottky barrier[2], has been of increasing interest for creating high-breakdown voltage electronic devices and mid-infrared optelectronic devices. Several authors have reported epitaxial growth of InAlAsSb by molecular beam epitaxy (MBE)[3-5]. However, only one group has reported the metalorganic chemical vapor deposition (MOCVD) growth of InAlAsSb[6]. They adjusted arsine (AsH3) flow rate to achieve lattice matching, but no other growth details were reported. However, for the practical use of MOCVD grown InAlAsSb layers, a fuller understanding of the growth process is necessary because adequate composition control is essential. We note that several reports have examined the device application of InAlAsSb layers. When InAlAsSb was applied as a Schottky barrier layer in the InP-based high electron mobility transistor (HEMT) structure instead of InAlAs, the breakdown voltage was improved[7]. We have also studied the epitaxal growth of the HEMT structure using MOCVD and reported that the introduction of InP/InAlAs Schottky barrier layer, whose InP layer acts as a recess-etch-stop layer, into the HEMT structure drastically improves the uniformity of its threshold voltage (Vth) and transconductance (gm)[8]. Although the combination of InP and InAlAsSb is expected to improve HEMT device performance, no report has discussed the fabrication of HEMT structures with InP/InAlAsSb Schottky barrier layers.
Z4.3.2
This paper studies the composition and growth rate of MOCVD grown InAlAsSb layers at various group-V flow rates. The decomposition characteristics of group-III sources during gro
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