Power-Dependent Investigation of Photo-Response from GeSn-Based p-i-n Photodetector Operating at High Power Density.

Chiao Chang,Imad Agha,Joshua R Hendrickson,Richard A Soref,Greg Sun,Hung-Hsiang Cheng,Zairui Li,Gary A Sevison,Jay Mathews

doi:10.3390/ma15030989

Abstract

We report an investigation on the photo-response from a GeSn-based photodetector using a tunable laser with a range of incident light power. An exponential increase in photocurrent and an exponential decay of responsivity with increase in incident optical power intensity were observed at higher optical power range. Time-resolved measurement provided evidence that indicated monomolecular and bimolecular recombination mechanisms for the photo-generated carriers for different incident optical power intensities. This investigation establishes the appropriate range of optical power intensity for GeSn-based photodetector operation.

Highlights

With the expansion of group-IV elements to include Sn, the prospect of achieving efficient group-IV photonic devices, such as photodiodes (PDs) and light emitting diodes (LEDs) that can be integrated on Si substrates in a CMOS compatible process, becomes much brighter
This behavior can can be understood in terms of the optical ababsorption whichisisstronger strongeratatshorter shorter wavelengths wavelengths because because the sorption which the optical optical transition transition occurs occurs between betweendeeper deeperconduction conductionand andvalence-band valence-bandstates stateswith withhigher higherdensities densitiesof ofstates, states,but butat at the same time, the number of photons that can be absorbed is less at shorter wavelengths for the same time, the number of photons that can be absorbed is less at shorter wavelengths fixed incident power
We modeled the index of refraction of GeSn using the method presented by Tran et al [28] and used the transfer matrix method to calculate the absorption in the GeSn layer

Summary

Introduction

With the expansion of group-IV elements to include Sn, the prospect of achieving efficient group-IV photonic devices, such as photodiodes (PDs) and light emitting diodes (LEDs) that can be integrated on Si substrates in a CMOS compatible process, becomes much brighter. GeSn PDs that has not been studied is their performance under various incident power conditions. InGaAs PDs have been used to fulfill this need to some extent, but InGaAs is known to be a poor thermal conductor—a severe material limitation. With almost 10 times better thermal conductivity, PDs made of GeSn are better. Materials 2022, 15, 989 some extent, but InGaAs is known to be a poor thermal conductor—a severe material lim of 9 itation. With almost 10 times better thermal conductivity, PDs made of GeSn are better suited for high-frequency RF applications. In this investigation, we perform a study of the power-dependence of photo-responsivity in GeSn PDs over their active absorption wavesuited range

Methods

Results

Discussion

Conclusion