An epoxy-modified urethane rubber mixed with carbon particles is now chosen as the millimeter-wave absorber material in our study. The absorption characteristics of the absorber is measured under temperature changes. The weatherability of our absorber is also clarified based on absorption characteristics, thickness and hardness of the sample. As a result of the temperature characteristics of the absorber, the difference of the maximum absorption frequency under temperature changes is about 1 GHz, however the absorption of 20 dB or more is obtained between 54 and 58 GHz. The result of accelerated artificial exposure test is that 2.8% of the thickness of our sample is shrunk after 1000 hour exposure, and the hardness of rubber is hardened with increasing test time. It is also confirmed that the deterioration of the absorption ranges from 1 to 3 dB, although the absorption of about 20 dB is kept at the frequency range. As a consequence, it is confirmed that the wave absorber using the epoxy-modified urethane rubber mixed with carbon particles has good weatherability including our desired temperature characteristics, and it is suitable for outdoor use.

We fabricated a new lateral Power MOS FET with an SOI structure formed by a solid phase epitaxy method which has a buried gate under the channel layer and a trench gate/drain. We studied the temperature dependence of the Vg-Id characteristic and Vd-Id characteristic in the temperature range of from 27 to 150. In the Vd-Id characteristic, the drain current decreases as the temperature increases in the saturation region, but the drain current increases as the temperature increases in the linear region. Zero-temperature-coefficient bias point of Vg-Id characteristic was 0. 3 V. And, the threshold voltage variation was -2. 8 mV/. In the Vd-Id characteristic, the drain current decreases as the temperature increases. The specific on-resistance was obtained in the linear region of the Vd-Id characteristic. The specific on-resistance variation was 0. 3 mWmm2/. The temperature characteristics of this device are as good as those of the conventional MOS FET.