A microfabricated sun sensor using GaN-on-sapphire ultraviolet photodetector arrays

A miniaturesensor for detecting the orientation of incidentultraviolet light was microfabricated usinggallium nitride (GaN)-on-sapphire substrates and semi-transparent interdigitatedgoldelectrodes for sun sensing applications. The individual metal-semiconductor-metalphotodetector elements were shown to have a stable and repeatable response with a high sensitivity (photocurrent-to-dark current ratio (PDCR) = 2.4 at −1 V bias) and a high responsivity (3200 A/W at −1 V bias) underultraviolet (365 nm)illumination. The 3 × 3 GaN-on-sapphireultravioletphotodetector array was integrated with agold aperture to realize a miniature sunsensor (1.35 mm × 1.35 mm) capable of determining incident light angles with a ±45° field of view. Using a simple comparative figure of merit algorithm, measurement of incident light angles of 0° and 45° was quantitatively and qualitatively (visually) demonstrated by the sunsensor, supporting the use of GaN-based sunsensors for orientation, navigation, and tracking of the sun within the harsh environment of space.
Source: Review of Scientific Instruments - Category: Physics Authors: Source Type: research