Influence of Barrier Width on QWIP Operating Voltage

Abstract

Introduction. Quantum well infrared photodetectors (QWIP) are characterized by a wide application range. A large market demand for such photodetectors determines the importance of elucidating the principle of their operation.Aim. To carry out a research study into the influence of the AlGaAs potential barrier surrounding GaAs quantum wells on the QWIP operating bias voltage in the long-wavelength region of the spectrum (8…10 μm).Materials and methods. QWIP experimental samples were manufactured based on the GaAs/AlGaAs semiconductor material system using molecular beam epitaxy. The photosensitive (active) region of the structures contained 50 GaAs quantum wells with a thickness of 50 Å thick separated by AlGaAs barriers. Quantum wells were doped in situ with silicon as a donor impurity. The wavelength of the maximum spectral sensitivity of all samples ranged within 8…9 μm. The barrier width was the variable parameter. After passing the planar modification process route, the current–voltage characteristics were measured in all structures.Results. Reduction in the barrier thickness is capable of shifting the peak of photosensitivity towards the region of lower bias voltages with a slight increase in the dark current values.Conclusion. The study of the influence of the applied bias voltage presents both scientific and practical interest. On the one hand, the results improve the current understanding of the behavior of the dark current in QWIP. On the other, they provide the possibility of managing the maximum current sensitivity, shifting it towards the region of the required operating voltages of the multiplexers.

Keywords

• quantum well infrared photodetectors
• dark current
• spectral photosensitivity
• current–voltage characteristics