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中原大學九十三學年度博士班入學招生考試
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| 93年69月9日 8:30~10:00 電子工程學系電子組 | 誠實是我們珍視的美德， 我們喜愛「拒絕作弊，堅守正直」的你！ |
| 科目：半導體元件 |
| ˇ可使用計算機，惟僅限不具可程式及多重記憶者 □不可使用計算機 | ||
| 1. | A Hall measure measurement was done on the Si sample shown in Fig. 1. The following data were obtained: | |
 (20%) |
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| The Hall coefficient factor is known and equal to 1.18. Find: | ||
| (a) | the conductivity type; | |
| (b) | the majority carrier concentration; | |
| (c) | the Hall mobility; | |
| (d) | the conductivity; | |
| (e) | the diffusion constant. | |
 |
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| 2. | The temperature dependence of the specific conductivity 
and the Hall constant 
of a certain semiconductor were measured and are shown in Fig. 2. Explain
the behavior of
and
at temperatures higher than 600 K. (20%) |
|
 Fig.2 |
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| 3. | Fig. 3 shows the position of the Fermi level 
and the occupation of the bands for two conduction types of the same semiconductor. |
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| (a) | How can these types of semiconductors be achieved? (5%) | |
| (b) | A diode formed with the semiconductors mentioned above can be operated in a negative conductance mode to provide amplification or oscillation at microwave frequencies in a proper circuit. Draw the band diagrams at thermal equilibrium, reversely biased, weakly forward biased and strongly forward biased, respectively. The mechanisms through which the current conducts should also be explained. (10%) | |
| (c) | (c) Plot the static current-voltage (I-V) characteristics of the above junction. (10%) | |
 Fig.3 |
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| 4. | Plot (a) the charge distribution, (b) electric-field distribution, and (c) potential distribution of an ideal MOS diode with p-type substrate under inversion. (15%) | |
| 5. | Give four reasons, as a semiconductor, why GaAs is more attractive for microwave devices than Si is. (20%) | |
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