The proposed innovation is the development of a novel dual band detector responding in both the UV and IR regions, based on a GaN/AlGaN heterostructure. The IR response is based on HEterojunction Interfacial Workfunction Internal Photoemission (HEIWIP) detectors, which have been demonstrated using AlGaAs/GaAs structures. By also using interband transitions, response in the UV range can be incorporated into the device. A GaAs detector structure was shown to respond in both the NIR and FIR regions demonstrating the dual band capability. A material system change to GaN/AlGaN is expected to shift the NIR response into the UV range providing a UV-IR dual band detector. By varying the material compostion the spectral ranges can be tailored for the specific application. The initial detectors will operate in the 0.2 - 0.35 micron UV range and 8--14 micron IR range. The proposed detector would allow simultaneous imaging of both spectral ranges using a single detector array. This would provide a large advantage over current approaches which use separate detectors to image the two regions. By varying the Al fraction in the AlGaN, the detector can be easily extended to cover the range up to 40 microns.
Benefits: The proposed devices would be useful in numerous applications. The use of GaN would have the advantage over HgCdTe of allowing simultaneous detection in the UV and IR with a single detector. This would eliminate many difficulties in developing pixel-collocated detector arrays covering both bands. A multiband detector can be used as a remote thermometer by using the spectral information from the difference in the signals for the two bands. In applications such as mine detection, the use of images in two different spectral bands can aid in the detection and reduce the number of false positives. The UV portion of the detector could be used to detect muzzleflash to locate the position of enemy troops, while the IR range is useful for determining troops and functional vehicles and armored cars, etc. The proposed device would have the ability to produce separate images of the psectral ranges or a single cmbined image. This would be a significant improvement on the current systems using two separte detector arrays. Although GaN intraband devices are still in the early stages of development, the proposed detector would be highly relevant in other device efforts such as a GaN QWIP or QCL.
Keywords: infrared, UV, GaN, heterojunction, detector, dualband
