GaAs/AlGaAs quantum well infrared photodetector with low noise

Abstract

A novel kind of multi-quantum well infrared photodetector(QWIP) is presented. In the new structure device, a p-type contact layer has been grown on the top of the conventional structure of QWIP, then a small tunneling current is instead of the large compensatory current, which made the device low dark current and low noise characteristics. The measured result of dark current is consistent with the calculated result, and the noise of the new structure QWIP is decreased to one third of the conventional QWIP. CLC number;TN362 Document code..A Article ID. 1673-1905(2005)01-0037-03GaAs/A1GaAs multi-quantum wells infrared photodetector(QWIPs) relating to the single device and the focal plane arrays were developed very fast in last ten years, even then the performance of QWIPs for 8~12 /,m are not as good as MCT's E1-33 . To improve the performance of QWIPs, a novel kind of structure of QWIPs is reported in the paper. In the new structure device, a ptype contact layer has been grown on the top o{ the conventional structure of QWIP, then a small tunneling current is instead of the large compensatory current, which makes the device low dark current and low noise characteristics.QWIPs are operated by photoexcitation of electrons between ground and first excited or continuing state subbands of multi-quantum wells (MQWs) which are artificially fabricated by placing thin layers of two different high-bandgap semiconductor materials alternately, such as n-type GaAs and i-type A1GaAs. The bandgap discontinuity of two materials creates quantized subbands in the potential wells associated with conduction bands or valence bands. The structure parameters are designed so that the photo-excited carriers can escape from the potential wells and be collected as photocurrent Jp shown in Fig. 1. When the electrons are excited from the ground states, the same number of empty quantum states are generated, which should be refilled to keep the photo absorption. Therefore, there is a large compensation recombination current J, which is offered by electrode, through the device structure. The dark current in conventional GaAs/A1GaAs QWIPs is combination of sequential tunneling, thermally assisted tunneling and thermionic emission c~. The sequential tunneling that happened between the ground state could be ignored under the low temperature,such as 77 K. It means that the * Supported by National "973" program(TG2000068302) *

Research on the Electronic Tunneling in Asymmetric Dual-Quantum-Well

“…Profit from the advancement of MBE (Molecular Beam epitaxy) technology recent years, the ability for ultra-thin films growth control was enhanced, the deep research on quantum tunneling devices design and fabrication was taken by many organizations. The quantum tunneling material and devices based on the quantum tunneling effect, for instance, THz diode [1][2][3][4] , QCL [5][6][7] and QWIP [8][9][10] etc, these devices had been applied widely. Generally, in the preparation of QCL and QWIP materials, several active cores were cascaded to enhance their tunneling effect, this cascade based on the carrier tunneling effect in dual quantum well, which was discussed in this paper.…”