Fabrication and Optoelectronic Characterization of InAsPSb/InAs Mid-infrared Photodetectors
Date Issued
2010
Date
2010
Author(s)
Lo, Shih-Wei
Abstract
We study the fabrication and the properties of InAsPSb/InAs heterojunction p-i-n (p-InAsPSb/i-InAs/n-InAs) photodetectors. Three structures with different i layer thickness of 0.75 μm (C2759), 1.5 μm (C2758), 2 μm (C2866) were grown by gas source molecular beam epitaxy, and fabricated in devices with four different areas. The responsivity at a wavelength of 3 μm at room temperature increases obviously when the i layer thickness is increased from 0.75 μm to 1.5 μm. But the devices with 2 μm i layer thickness have much lower responsivities because of the large lattice mismatch of the InAsPSb layer.
The best performance in our devices is the device with an i layer thickness of 1.5 μm and an area of 500 × 500 μm2. Responsivities at room temperature in the 0.7-1.64 A/W range were obtained in the 2-3.5 μm wavelength range, corresponding to external quantum efficiencies within 50-67 %. If the 65 % transmittance of the surface of the devices is considered, the internal quantum efficiency can be as high as 100 %. And a peak of detectivity of 5.4 × 109 cm-Hz1/2/W was obtained at the wavelength of 3.05 μm. The ideal R0A of our 1.5-um-i-layer samples is 0.77 Ω-cm2. The best detectivity is expected to be 1.67 × 1010 cmHz1/2/W at 3.05 μm with a 100 % quantum efficiency.
Subjects
photodetectors
InAsPSb/InAs
responsivity
quantum efficiency
detectivity
Type
thesis
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