High-speed, low-noise metal–semiconductor–metal ultraviolet photodetectors based on GaN
D. Walker(Northwestern University), E. Monroy(Northwestern University), Patrick Kung(Northwestern University), Jun Wu(Northwestern University), M. Hamilton(Northwestern University), F.J. Sánchez(Northwestern University), J. Diaz(Northwestern University), Manijeh Razeghi(Northwestern University)
Cited by 188
Abstract
We present the fabrication and characterization of nonintentionally doped GaN and GaN:Mg Schottky metal–semiconductor–metal (MSM) photodetectors, grown on sapphire by metalorganic chemical vapor deposition. Low-leakage, Schottky contacts were made with Pt/Au. The devices are visible blind, with an ultraviolet/green contrast of about five orders of magnitude. The response times of the MSM devices were <10 ns and about 200 ns for GaN and GaN:Mg, respectively. The noise power spectral density remains below the background level of the system (10−24 A2/Hz) up to 5 V, for the undoped GaN MSM detector.