Air Force scientists have improved the performance of infrared (IR) detectors by using a passivation layer with dopant to reduce/eliminate leakage currents. The patented technology is available via license agreement to companies that would make, use, or sell it commercially.
Manufacturing an IR photodetector often exposes the sensor to processes, materials, and techniques that limit their operating range or hinder their performance.
When fabricating such detectors, the processes used can alter the semiconductor absorption material at the surface. This can create a conductive surface layer that bypasses the path through which bulk electrical current should flow.
In such instances, surface leakage current flows through the conductive surface layer instead, significantly hampering reliable operation.
The challenges posed by surface leakage current can be particularly prevalent in devices using p-type absorption materials, where the etching process results in pinning at the surface. This pinning, in turn, leads to an accumulation of electrons near the surface such that the p-type material becomes an n-type material, leading to surface inversion.
Standard passivation layers can act as a protective film but are typically not doped. Also, they must be epitaxially regrown, resulting in a more complicated fabrication process.
The researchers have developed a method to compensate for the effects of the fabrication process on the reliability and operation of photodetectors. More specifically, a uniform passivation layer is deposited on the infrared detector where leakage current is most likely to occur – typically on the sidewalls if the detector is of a mesa construct.
The dopant material in the passivation layer is diffused into the detector material using standard methods. The passivation layer can be retained or later removed by dry or wet etching.
- Passivation layer reduces or eliminates the surface leakage current and dark current
- Higher performance materials can be used as a part of the device structure, such as a p-type absorption material
- When using a p-type absorption material, the thickness of the absorption material can be increased to improve quantum efficiency
- Compatible with both homojunction and heterojunction diode structures and various barrier materials
- Businesses can commercialize the technology by licensing U.S. Patent 10,297,708 from the Air Force
- License fees paid to the Air Force are negotiable
- Businesses that license the technology may have the opportunity to pursue collaborative research with the inventors
- Testing data may be available to companies evaluating the technology
- TechLink guides businesses through evaluation and licensing; services provided at no cost