| Autor: |
Tan, S. W., Chen, H. R., Chen, W. T., Hsu, M. K., Lin, A. H., Lour, W. S. |
| Předmět: |
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| Zdroj: |
Journal of Applied Physics; 2/1/2005, Vol. 97 Issue 3, p034502, 7p, 2 Black and White Photographs, 6 Diagrams, 3 Graphs |
| Abstrakt: |
Fabrication, characterization, and theoretical modeling of two-terminal and three-terminal heterojunction phototransistors ( 2T- and 3T-HPTs) based on InGaP/GaAs are reported. For a current–bias 3T-HPT, an independent current flowing into or out of base electrode is employed to modulate the operating point of a heterojunction bipolar transistor (HBT). The operating point of a HBT in the presence of a positive bias current can be tuned to a higher current level where the current gain is larger. It is found that the optical gain increases from 28.4 for a 2T-HPT to 34 for a 3T-HPT with a bias current of 10 μA. The achievement of tunability of the operating point of a HBT has also been attempted with an independent voltage source. Nevertheless, our work reveals that the p–i–n photocurrent generated within the B–C region contributes very little to the final collector photocurrent for a voltage–bias 3T-HPT, resulting in a rather small optical gain in the range 0.8–1.6. A simple equivalent circuit model is developed to explain the differences between a current– and a voltage–bias 3T-HPT. Our calculated results are in good agreement with the experimental ones. [ABSTRACT FROM AUTHOR] |
| Databáze: |
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