Temperature dependence of the performance of charge-sensitive infrared phototransistors

Department of Basic Science, University of Tokyo, Komaba 3-8-1, Meguro-ku, Tokyo 153-8902, Japan
Journal of Applied Physics (Impact Factor: 2.18). 04/2009; 105(6):064517 - 064517-8. DOI: 10.1063/1.3087579
Source: IEEE Xplore


The performance of charge-sensitive infrared phototransistors ( λ∼14.7 μ m ) is studied at temperatures of up to 30 K. The devices, with a 16×4 μ m 2 photoactive area, are fabricated in GaAs/AlGaAs double-quantum-well structure. An excellent specific detectivity D*=9.6×1014 cm   Hz 1/2/ W is derived in a T range of up to T=23 K . Experimental results are theoretically studied based on WKB approximation, in which photogenerated holes in the floating gate (FG) are recombined with thermal emission or thermally assisted tunneling from the outside of FG through the barriers. The model well reproduces the experimental results, including the vanishing of photosignal at 30 K under 280 fW incident radiation. The model is used to predict a temperature-dependent specific detectivity D* in ideal devices free from 1/f noise.

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    • "The maximum operating temperature is expected to be roughly proportional to the photon energy. Noting T ≈ 25 K for λ = 15 μm (hν = 84 meV) [42], the temperature is expected to range from T ≈ 50 K for λ = 8 μm (hν = 154 meV) to T ≈ 4 K for λ = 80 μm (hν = 15.4 meV). Owing to the simple device structure, CSIPs are promising for integration to large-scale arrays. "
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