InSb MOS Diodes on a Si (111) Substrate Grown by Surface Reconstruction Controlled Epitaxy Azusa Kadoda, Tatsuya Iwasugi, Kimihiko Nakatani, Koji Nakayama, Masayuki Mori and Koichi Maezawa Graduate School of Science and Engineering, Univ. of Toyama 3190 Gofuku, Toyama 930-8555, Japan Phone: +81-76-445-6725 E-mail: maezawa@ieee.org 1. Introduction Recently, III-V compound semiconductors have been attracted much attention as a channel material for post scaling era. Among them, InSb is one of the most promis- ing candidates because it features highest electron mobility of 78,000 cm 2 /(Vs) and high saturation velocity of 5x10 7 cm/s. High performance HEMTs based on InSb/InAlSb material system have been already demonstrated [1]. How- ever, growth of high quality InSb on Si is difficult due to the large lattice mismatch of 19.3%. So far, most of the devices reported were grown on GaAs substrates. Most recently, we have demonstrated that good InSb epitaxial films can be grown on Si (111) substrates using MBE via InSb bi-layer with special care to the surface re- construction [2]. Very high mobility of 38,000 cm 2 /(Vs) can be obtained for relatively thin (1.2 μm) InSb on Si [3]. In this paper, we report on Al 2 O 3 /InSb MOS diode charac- teristics fabricated on InSb films grown on a Si (111) sub- strate using this technique. 2. Epitaxial Growth Our growth technique is based on the finding that the InSb layer grown on a Si (111) substrate is rotated by 30 degree with respect to the substrate under a certain initial condition [2]. Figure 1 shows the schematic view of the Si atoms in a (111) surface with two InSb unit cells, non-rotated and rotated ones. As seen in the figure, 30-degree rotation drastically reduces the lattice mismatch from 19.3 % to 3.3 %. This reduction improves crystal quality of the epitaxial layers quite well. The details of the growth procedure were reported pre- viously [4]. Here, we describe the essence of the growth technique. A key to rotate the InSb epitaxial layer is the InSb initial bi-layer prepared by adsorption of 1 monolayer (ML) Sb onto In-induced surface reconstruction. Special care is taken here to the phase of the surface reconstruction. The InSb films were then grown by two-step growth pro- cedure on this bi-layer. The growth temperature was 200 C for the first layer, and 440 C for the second layer, respec- tively. Good quality epitaxial films (thickness 1-μm) were prepared by this growth technique. They were slightly n-type though no impurity was intentionally doped. The electron concentration and the electron mobility were esti- mated to be around 2x10 16 cm -3 and 38,000 cm 2 /(Vs), re- spectively, from the data grown under the same condition. 3. Al 2 O 3 /InSb MOS Diode To investigate the possibilities of InSb MOSFETs on Si substrates we fabricated Al 2 O 3 /InSb MOS diodes on epi- taxial films grown using above technique. An Al 2 O 3 insu- Fig. 1. Schematic view of the Si atoms in a (111) sur- face with rotated and non-rotated InSb unit cells. Fig. 2. Microphotograph and schematic cross-section of the fabricated Al 2 O 3 /InSb MOS diode. -852- Extended Abstracts of the 2010 International Conference on Solid State Devices and Materials, Tokyo, 2010, pp852-853 I-3-2