Mechanisms of photocurrent generation in SiGe/Si HIP infrared photodetectors

Abstract

We study the mechanisms of photocurrent generation in the SiGe/Si heterojunction internal photoemission (HIP) infrared photodetectors and present a qualitative model. It has been shown that the performance of our devices depends significantly on the applied bias and the operating temperature. The device presented here allows us to tune the cut-off wavelength between 28.3 µm and 17.8 µm by changing the potential difference across the device.

Study on the long wavelength SiGe/Si heterojunction internal photoemission infrared photodetectors

“…Depending on the applied bias, contribution of each current to the device current either increases or decreases. Further discussion on these can be found in reference [23]. (4), and shows a good agreement with the experiment.…”

On the theory of internal photoemission in heterojunctions

“…7, L p = 38 (12) Å , L e = 1200 (600) Å , hx = 1 (1) meV were obtained for curve 1 (2). Obtained values are self-consistent: When the device is negatively biased (curve 2 case), since the reverse currents increases [18], the possibility of elastic and semi-elastic collisions increases. Therefore, the mean free paths for collisions decrease while the energy loss per collision term is constant.…”

“…For more detailed information on the samples and the experiments, Refs. [17,18] and/or [12] should be seen. Fig.…”

“…Note that the internal photoemission itself is a voltage independent process [19]; however, the voltage dependency here comes from the effect of the applied bias on the band and the photocurrent mechanisms in the structure. Detailed discussion on the photocurrent generation mechanisms has been given elsewhere [18]. In the fitting process, d = 382 Å , N A =2.1 · 10 19 cm À3 , C*=1 · 10 À10 , M = 0.919 (= 0.49/0.533), and corresponding E F = 51 meV were used as unchanged parameters.…”