Lateral collection structure for planar type InGaAs infrared detector

This article presents the fabrication of the front-illuminated planar type InGaAs infrared detector based on the lateral collection structure. The detector with the cutoff wavelength 1.7μm was fabricated on the NIN-type InP/InGaAs/InP hetero-structure materials with sealed-ampoule method using Zn3P4 as the diffusion source. And the detector with the dimension of 460μm×1000μm consists of four lateral collection regions and the width of each region is 15μm. Furthermore, the electrical properties and photo response characteristics were investigated between detectors with the lateral collection structure and normal structure. The Laser beam induced current (LBIC) map shows that the photoresponse of lateral collection InGaAs detector at 296 K is quite uniform and the photoresponse signals generated in the lateral collection regions are the same as them in PN junction regions. The lateral collection regions disappear from view since the electron/hole pairs generated in the regions are all collected by the electrical field of depletion region. It turns out that the average peak detectivity and the density of dark current of the detectors with lateral collection structure and normal structure is 3.22×1012 cm·Hz1/2/W and 3.00×1012 cm·Hz1/2/W, 4.85 nA/cm2 and 22 nA/cm2 at -100 mV respectively. Therefore, the lateral collection structure could substantially reduce the dark current by 70% compared with the normal structure.