Novel III-V heterostructures and designs for high-performance avalanche photodiode devices

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An avalanche photodiode (APD) is a specialized semiconductor device used for the detection of light and, in**certain applications, even individual photons. The APDs are therefore typically used in various applications**requiring sensitive detection of light. They have been successfully manufactured for operation at different**wavelengths, for ranging applications, and various light sensing solutions. A common feature of these devices**is a multiplication region: a region of very high electric field strength in which excited photo-current causes a**cascade of impact ionizations yielding a significantly amplified signal at the anode and cathode. There are**several applications for APD devices in the wavelength range of 1.5microns. The InP-based epitaxial materials**have been perfected to optimize the APD performance using InGaAs and InP heterostructures. The doping**profiles have been obtained by combining epitaxial doping and diffusion doping technique in these materials.**To expand into new applications it is important to further improve the performance of such III-V APDs and**complement the available baseline products. Specific areas for improvement are dark currents (bulk and**surface), steeper I-V curve in the avalanche region so the APD can be operated more safely further from the**breakdown voltage, and lower intrinsic noise equivalent power for better signal-to-noise ratio (SNR) when**receiving ultra-low light levels and enabling further ranging in laser-range finder applications. APDs require**exceptional design and process controls since the electric fields that initiate avalanche gain have very tight**requirements and the interaction of the materials and doping levels of the various layers needed to create a III-V**APD are complex with a narrow range of values that can be expected to yield good performance. This CRD**project will allow the optimization of the APD device performance by designing novel heterostructure**strategies with better optimized AlInAs/InGaAs/InP epilayers and doping designs.