Abstract
We present structural, optical, and transport characterization of long wave infrared hot electron transistor (IHET) based on doped quantum wells of InGaAs/AlGaAs. The atomic resolution images and x-ray diffraction patterns verified a lattice matched and band-gap engineered device structure of IHET. Measured values of the photocurrent were less than the theoretically expected values and indicated a loss of photocurrent between the base of the IHET and the collector. A higher filter height due to high unexpected dopant in the filter barrier was suggested as a possible cause of the current loss. Photoluminescence data in the near infrared showed the existence of such a dopant.
Highlights
The research and development of long wave infraredIRdetectors have included extrinsic doped germanium, PbSnTe, III–V semiconductor quantum well IR photodetectorsQWIPs, and HgCdTe.1 One of the critical goals remains to be that of robust low cost detectors as well as those with room or near room temperature operation.1,2 Wide variety of QWIPs has been developed, and large format, high performance focal plane arrays have been made
The key feature of an IHET is AlGaAs filter layer located between base contact and collector contact,6 which acts as a high-pass filter for the photocurrent and blocks the tunneling dark current, with resulting satisfactory detectivity
We present here theoretical and experimental investigations of an IHET structure that was characterized by TEM, XRD, and PL
Summary
The research and development of long wave infraredIRdetectors have included extrinsic doped germanium, PbSnTe, III–V semiconductor quantum well IR photodetectorsQWIPs, and HgCdTe. One of the critical goals remains to be that of robust low cost detectors as well as those with room or near room temperature operation. Wide variety of QWIPs has been developed, and large format, high performance focal plane arrays have been made. Despite the well developed mature GaAs technology, relatively low operating temperature due to the high thermal generation rate of the QWIPs are under improvement. The thermal generation rate can be reduced by better detector design such as increasing a barrier height, or placing a hot electron energy filter.. The key feature of an IHET is AlGaAs filter layer located between base contact and collector contact, which acts as a high-pass filter for the photocurrent and blocks the tunneling dark current, with resulting satisfactory detectivity.. By accepting only electrons at particular energies, the filter reduces the dark current and increases the photocurrent to dark current ratio at the collector. Both the operating temperature and the responsivity of the detector can be increased. The dark current was calculated, and IHET structures were grown, and the structural, optical, and transport properties were investigated
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