Confined and interface optical phonon emission in GaN/InGaN double barrier quantum well heterostructures.

Ahmed Mohamed,Mitra Dutta,Michael Stroscio,Kihoon Park,Can Bayram,Chih-Chun Chien

doi:10.1371/journal.pone.0214971

Ahmed Mohamed, Mitra Dutta + Show 4 more

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https://doi.org/10.1371/journal.pone.0214971

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Abstract

In GaN-based high electron mobility transistors (HEMTs), the fast emission of longitudinal optical (LO) phonons can result in the formation of hot spots near the gate region where high electric fields produce hot electrons. In this work, we investigate the probability of phonon emission as a function of electron energy for confined and interface (IF) phonon modes for wurtzite GaN/InGaN/GaN heterostructures. Hot electrons radiate optical phonons which decay, anharmonically, into acoustic phonons that are essentially heat carriers. Herein, phonon engineering concepts are introduced which facilitate thermal management through the production of polar optical phonons. Some of the electrons near a semiconductor gate which manifests a strong electric field, are accelerated and the resulting hot electrons will produce confined and interface modes when the electrons are incident on a suitably-placed quantum well. This paper focuses on the production of confined and interface phonons. It is shown that interface modes may be preferentially produced which lead to elongated, lower-temperature hot spots.

Highlights

III-nitride semiconductors are technologically important materials and as a result of their large bandgap energies, they are suitable for the optoelectronic intersubband devices ranging from the ultraviolet to the near infrared [1]
It is shown that inserting a GaN/In0.15Ga0.85N/GaN quantum well in the hot spot region of a GaN high electron mobility transistors (HEMTs), results in the emission of confined and interface phonons instead of bulk phonons as a result of emission from hot electrons, the phonons can be engineered to enhance the production of fast-moving interface phonons
It is shown that by quantum engineering of the inserted GaN/InGaN/GaN quantum well (QW) that the dominant phonon emission channel is that of interface phonon emission

Summary

Introduction

III-nitride semiconductors are technologically important materials and as a result of their large bandgap energies, they are suitable for the optoelectronic intersubband devices ranging from the ultraviolet to the near infrared [1]. Phonons of confined and interface modes coexist in certain regions in GaN/InGaN wurtzite heterostructures [13,14,15]. The dispersive behavior of Eqs (15) and (16) shows that the confined modes usually have infinite solutions for given n and q in the intervals [ω1z,ω1t] and [ω1lz,ω1lt], only a certain number of confined modes are considered at given n and q It is evident from the dispersion curves that the scattering rates increase due the strong presence of the confined phonons. The strong dependence of the scattering rates on the dispersion relation and the values of the above resonance frequencies help us predict the energy required to emit TO-like and LO-like phonons.

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Discussion

Conclusion