# Design and analysis of high electron mobility transistor (HEMT) inspired III-V electro-optic modulator topologies

## TL;DR

This paper proposes HEMT-inspired III-V electro-optic modulator designs leveraging high electron mobility for potentially superior performance over silicon photonic modulators, with analysis of electroabsorption and electrorefraction effects.

## Contribution

It introduces novel HEMT-inspired topologies for III-V electro-optic modulators and provides a framework for optimizing electroabsorption and electrorefraction mechanisms.

## Key findings

- Electrorefractive modulation index is comparable to silicon modulators.
- High electron mobility enables higher modulation rates.
- Design framework for selective modulation mechanism leveraging 2DEG interactions.

## Abstract

III-V heterostructure based high electron mobility transistors (HEMTs) offer superior performance as compared to CMOS silicon transistors owing to the high mobility in the 2D electron gas (2DEG) channel at the heterostructure interface. Gallium nitride (GaN) based HEMTs are also suitable for high power and high temperature applications. GaN has a rich offering of material properties spanning domains of nonlinear optics, piezoelectric micro-electro-mechanical systems (MEMS), and monolithic microwave integrated circuits (MMICs). In this paper, we propose HEMT inspired III-V electro-optic modulator topologies that could potentially outperform silicon photonic modulators. We analyze the electroabsorption and electrorefraction on account of the 2DEG interaction with light and present a design framework to selectively leverage the desired mechanism of modulation. Our analysis suggests that modulation index of electrorefractive modulation in a HEMT-like structure is comparable to silicon photonic modulators, albeit with much higher electron mobility and thereby much higher modulation rates.