Distinction investigation of InGaAs photodetectors cutoff at 2.9 μm

Using double heterojunction structure with linearly graded InxAl1–xAs as buffer layer and In0.9Al0.1As as cap layer, wavelength extended In0.9Ga0.1As detectors with cutoff wavelength of 2.88 μm at room temperature have been grown by using gas source molecular beam epitaxy, their characteristics have been investigated in detail and compared with the detectors cutoff at 2.4 μm with similar structure as well as commercial InAs detectors. Typical resistance area product R0A of the detectors reaches 3.2 Ω cm2 at 290 K. Measured peak detectivity reaches 6.6E9 cm Hz1/2/W at room temperature.