Quantifying Temperature-dependent Substrate Loss in GaN-on-Si RF Technology

TL;DR

This paper evaluates how substrate resistivity affects temperature-dependent substrate loss in GaN-on-Si RF technology through experimental device simulations, providing benchmarks for different resistivities and geometries.

Contribution

It introduces an experimentally validated simulation framework to quantify temperature-dependent substrate loss in GaN-on-Si RF devices, considering various resistivities and geometries.

Findings

High resistivity Si substrates show pronounced temperature dependence above 150°C.

GaN-on-high resistivity Si has lower substrate loss at frequencies above X-band.

GaN-on-low resistivity Si is more temperature-insensitive and has lower substrate loss at lower frequencies.

Abstract

Intrinsic limits to temperature-dependent substrate loss for GaN-on-Si technology, due to the change in resistivity of the substrate with temperature, are evaluated using an experimentally validated device simulation framework. Effect of room temperature substrate resistivity on temperature-dependent CPW line loss at various operating frequency bands are then presented. CPW lines for GaN-on-high resistivity Si are shown to have a pronounced temperature-dependence for temperatures above 150{\deg}C and have lower substrate losses for frequencies above the X-band. On the other hand, GaN-on-low resistivity Si is shown to be more temperature-insensitive and have lower substrate losses than even HR-Si for lower operating frequencies. The effect of various CPW geometries on substrate loss is also presented to generalize the discussion. These results are expected to act as a benchmark for temperature dependent substrate loss in GaN-on-Si RF technology.