Comparative study of metamorphic InAs layers grown on GaAs and Si for mid-infrared photodetectors

Abstract

We report a comparative study of metamorphic InAs p-i-n photodetectors epitaxially grown on GaAs and Si by molecular beam epitaxy. Linearly graded InAlAs buffers were employed to bridge the high lattice mismatch between InAs and Si. Quantitative measurement for threading dislocation density (TDD) in the InAs layers grown on GaAs and Si has been performed using transmission electron microscopy and electron channeling contrast imaging, both of which revealed that the TDD of InAs/Si sample is similar to 35% higher than that of GaAs sample. Comparison of fabricated InAs p-i-n photodetectors indicated that reduction of threading dislocation density is crucial for low dark current and high responsivity mid-infrared photodetectors on Si.