Investigation of Multicolor and Simplified Quantum Well Infrared Photodetectors for MWIR and LWIR Detection

摘要

In this research program, we have investigated a four-stack, four- color quantum well infrared photodetector (QWIP), and studied the voltage distribution and temperature effect in this four-color QWIP. We have conducted a study on the quantum confined Stark-effect in an n-type QWIP. We have performed theoretical studies of the intersubband optical transitions in quantum dots and the design of GaAs/InGaAs and InAs/InAlAs quantum dot infrared photodetectors (QDIPs) for MWIR and LWIR detection. A new QWIP for very long wavelength infrared (VLWIR) applications has been investigated for 14-16 (micrometer) detection. Specific issues concerning device physics, detector design and device performance of the VLWIR QWIP are addressed. A VLWIR QWIP has been designed, fabricated and characterized. Two high performance multi-color, broadband QWIPs using digital graded superlattice barriers (DGSLB) for long wavelength infrared (LWIR) and broadband (BB) infrared detection have been demonstrated. We have also developed a high performance broadband (BB) In(0.26) Ga(0.74) As/Al(x) Ga(1-x)As QWIP using a linearly graded (LGB) Al(x) Ga(1-x) As barrier for LWIR detection. Theoretical study on the enhancement of quantum efficiency in a QWIP by using photonic crystal structure has also been carried out in this report.