Investigation of crystal growth on (111) InSb thin films to produce high performance Hall elements
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Investigation of crystal growth on (111) InSb thin films to produce high performance Hall elements Toshiaki Fukunaka and Takeki Matsui Department of Research and Development, Asahi Kasei Electronics Co. Ltd., Miyazaki, Japan
Shin-ya Matsuno Analytical and Computational Research Lab., Asahi Chemical Industry Co. Ltd., Shizuoka, Japan (Received 11 December 1997; accepted 12 March 1998)
The crystal growth of InSb thin films on mica substrates was investigated by conventional three temperature vacuum evaporation with varied SbyIn flux ratios and temperature programming for the substrate. The SbyIn flux ratio was varied from higher than 1.0 (about 2.0 is optimum), to less than 1.0 (about 0.7 is optimum), to again much higher than 1.0 during the stages of evaporation. The electromagnetic characteristics were investigated and x-ray analysis of the films at various stages was undertaken. The films obtained contained no excess In and they were (111) highly oriented in x-ray analysis, showing high electron mobility. These films were used to prepare high performance Hall elements.
I. INTRODUCTION
InSb has higher electron mobility than other semiconductor compounds, such as InAs and GaAs. Because of this property, thin InSb films are known to be advantageous for use as Hall elements or magnetoresistive elements and they have been gaining the increasing attention of researchers for use in devices such as position detectors or direct drive motors, or as the components of electronic equipment such as VTR’s, FDD’s, and CD-ROM’s. Two important parameters for the Hall effect of a semiconductor are the Hall coefficient (RH ) and Hall mobility (mH ). Figure 1 shows the arrangement to measure these two parameters. It consists of a test conductor A with a length l, width w, and thickness t (not illustrated), on which metal such as copper is deposited to form input electrodes a, a0 , and output electrodes b, b 0 . A voltage VHI is developed between the output electrodes when the input electrodes are connected to a constant current supply I, and a voltage VHV is developed when they are connected to a constant voltage supply V . The two voltages are represented by the following equations: VHI f 3 sRH ytd 3 B 3 I , VHV f 3 mH 3 swyld 3 B 3 V ,
varies greatly with temperature, and VHI is largely dependent on temperature in practical applications. On the other hand, the Hall mobility (mH ) in Eq. (2) is fairly independent with respect to temperature and almost all commercial InSb Hall elements are used under constant voltage. Hence, an InSb semiconductor having high Hall mobility rather than a high Hall coefficient is required. Since G¨unther’s proposal1 of a process to make thin film of IIIB 2 VB compound semiconductors by vacuum
(1) (2)
where B is the magnetic flux density of an applied external magnetic field, and f is a factor dependent on the configuration of the sample. As Eq. (1) shows, VHI is in inverse proportion to the thickness of the material through which the current flows,
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