Surya Prakash Gangiredla

It is known that every object above absolute zero (0 K) emits electromagnetic radiation. Therefore, it is possible, in principle, to observe any object if we have a device capable of capturing this radiation and converting it into an image, even when it is invisible to the human eye due to darkness or great distance. Infrared photodetectors serve this purpose by detecting radiation in the infrared region, which is less energetic than visible light. Infrared detection has numerous applications in LiDAR, night-vision imaging, optical communication, and environmental monitoring.

Among these devices, nanowire-based avalanche photodetectors (NW-APDs) are a particularly promising technology. Nanowires, which are wire-like structures approximately a thousand times thinner than a human hair, are utilized to detect light efficiently while significantly reducing material usage. Their unique geometry enhances light absorption and improves optical confinement and guiding within the device. The avalanche mechanism further enhances sensitivity, enabling the detection of even the smallest numbers of photons.

In this project, I will focus on the fabrication of nanowire-based avalanche photodetectors for extended short-wave infrared (e-SWIR) detection, targeting wavelengths between 1.7 µm and 2.5 µm. To achieve tunable detection in this range, InAs_1–xP_x/InP nanowire heterostructures may be employed. The fabrication process involves advanced semiconductor techniques, including MOCVD growth, sputtering, and lithography. This project will be carried out in collaboration with KTH Royal Institute and a company, IR Nova AB ( a leading Swedish-based company in the production of infrared cameras).

These detectors are increasingly becoming integral to modern technologies. A deeper understanding of their device physics and continued performance improvement will have a significant impact on society, supporting advances in sensing, communication, and sustainability through more efficient and energy-conscious photonic systems