Leakage currents limit the operation of high performance type II InAs/GaSb superlattice photodiode technology. Surface leakage current becomes a dominant, limiting factor to the ideal performance of a photodiode, especially at the scale of a focal plane array pixel (< 25 µm), and must be addressed. A reduction of the surface state density, unpinning the Fermi level at the surface, and appropriate termination of the semiconductor crystal are all aims of effective passivation. This work summarizes my studies of dielectric (organic and inorganic) passivation, aqueous and non-aqueous sulfur-based passivation, and semiconductor overgrowth passivation of type II InAs\GaSb superlattice mesa photodiodes. Passivation has resulted in increased R0A products and reduced dark current densities by reducing the surface trap density. Additionally, photoluminescence of similarly passivated type II InAs/GaSb superlattice and InAs and GaSb bulk material will be discussed. The use of an organic polymer was employed for surface passivation of MWIR and LWIR type II photodiodes. This passivation technique demonstrated near bulk limited R0A performance with extremely high surface resistivities. The importance of thorough sample cleaning, prior to passivation, is demonstrated as well. Some sample preparation suggestions are given to reduce the formation of oxides and adsorption of deleterious process contaminants on the semiconductor surface. In addition to work centered on surface passivation, type II photodetector performance characteristics will be analyzed and discussed. These will include capacitance voltage measurements done on type II superlattice photodiodes to identify record low residual impurity background concentration values, indicating very high quality material growth. Additionally, enhancement of the device quantum efficiency for LWIR photodetectors is shown through modeling and growth optimization. Two custom designed systems are also presented, which include a portable, reconfigurable infrared and UV camera system as well as a mid infrared free-space communications system operating at room temperature with a quantum cascade laser as the source and a mid infrared type II InAs/GaSb superlattice photodiode as the receiver.

Last modified

• 08/31/2018

Creator

• Andrew David Hood

DOI

• https://doi.org/10.21985/N2FD93

Subject

• Electrical and Computer Engineering

Keyword

• superlattices
• infrared
• passivation
• FPA
• photodetectors
• surface

Date created

• 2007-12-05

Resource type

• Dissertation

Rights statement

• In Copyright