Applied Physics

Transistors Turn On the Light

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Science  16 Jan 2004:
Vol. 303, Issue 5656, pp. 287
DOI: 10.1126/science.303.5656.287b

The field of optoelectronics usually requires the integration of separate devices with optical and electronic functionalities. The extra masking, patterning, and wiring processes involved in the integration add significantly to the fabrication time and therefore to the cost of the end product. Furthermore, as these “separates” need to talk to each other, there may also be a reduction in the device performance. Feng et al. have fabricated a heterojunction bipolar transistor based on an InGaP/GaAs structure that combines both functions—three-terminal electronic control and optical function—in one device. They demonstrate that as their transistor is turned on, it also emits light as the injected carriers recombine in the vicinity of the base layer contact. By modulating the current of the base layer contact, they also demonstrate the ability to switch the light emission at rates up to 1 MHz. Although this modulation rate is rather slow, but perfectly sufficient for display purposes, present wide-bandgap heterojunction transistors can now achieve switching rates of 450 GHz, indicating a possible use for these light-emitting transistors in optical communication networks. — ISO

Appl. Phys. Lett. 84, 151 (2004).

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