| Thermal imaging by infrared focal plane arrays (FPAs) has many military and commercial applications. So far, most infrared FPAs are based on HgCdTe or quantum well infrared photodetectors (QWIPs). HgCdTe suffers from difficult material growth, array non-uniformity, and high cost. N-type QWIPs are not sensitive to normal incidence. P-type QWIPs can detect normal incidence but their detectivity is low. On the other hand, with the many advantages they promise, QDIPs represent one of the alternatives for a next generation infrared detector.; The objective of this work is to grow high quality self-assembly InAs quantum dots, together with various matrix materials such as InP, GaInAs and AlInAs on InP substrates by low-pressure MOCVD for use in QDIP.; The quality of the grown materials has been appraised by structural, optical, and electrical characterization techniques. Next, n-i-n photoconductor structures based on the InAs/InP systems have been grown, fabricated, and tested. At 81K, photoresponse shows the peak wavelength at 6.4 mum. The highest detectivity of 1.0x1010cm. Hz1/2/W was achieved at bias 0.4 V. This is the first and best report of QDIP detectivity from InAs/InP system in the world! An AlInAs current blocking layer has been used, which reduced the dark current and the noise current dramatically. Peak detection wavelengths from 6.4 mum to 4 mum were demonstrated by dot engineering.; A 256x256 FPA based on the InP-based QDIP has been demonstrated for the first time in the world! Thermal imaging was achieved at 77K.; Several approaches for further improvement are discussed in the future work.; Mid-infrared lasers emitting from 3 to 5 mum also have many applications. Semiconductor lasers are well suited for these applications because of their intrinsic advantages of wide wavelength coverage, low cost, simplicity of operation, and compact packaging. High quality InAs, InAsSb, and InAsSbP materials on InAs substrates have been grown by LP-MOCVD for use in double-heterostructure and strained-layer superlattice infrared lasers. The quality of the grown materials has been appraised by structural, optical, and electrical characterizations. Lasers emitting from 3 to 5 mum have been optimized and measured. |
