Local Channel Temperature Measurements on Pseudomorphic High Electron Mobility Transistors by Photoluminescence Spectroscopy

Abstract

The technique of spatially resolved photoluminescence (PL) spectroscopy was used to determine the local channel temperatures on GaAs/GaInAs/GaAlAs pseudomorphic high electron mobility transistors. By focusing a laser beam onto the different regions of the DC-biased transistor, it is shown that the channel temperature can be determined from the energy shift of one of the peaks in the PL spectra, with a spatial resolution of about 1 pnm and a temperature resolution in the order of 1 'C. In particular, an asymmetry in the temperature distribution between the drain and source sides is observed. Using this approach, detailed temperature maps of the devices were obtained, as a function of the gate-source voltage VGS. These experimental temperature values are also compared with predictions derived from an analytical model of the thermal resistance in these devices.

Thermal Maps of GaAs P-HEMT: A Novel System Based on the Photocurrent Spectral Analysis

“…Several measurement techniques of device temperature are commonly used: electrical dc method [3], IR techniques [4], liquid crystal techniques [5], Raman spectroscopy [6], cathodoluminescence [7], and photoluminescence spectroscopy [8]. Many of these methods do not allow the exact evaluation of the channel temperature, since some of these techniques (such as [4] and [5]) are able to measure only the surface temperature of the device, while some other techniques (such as [7] and [8]) may be affected by carrier diffusion phenomena that tend to smear out the knowledge of temperature distribution.…”

“…Many of these methods do not allow the exact evaluation of the channel temperature, since some of these techniques (such as [4] and [5]) are able to measure only the surface temperature of the device, while some other techniques (such as [7] and [8]) may be affected by carrier diffusion phenomena that tend to smear out the knowledge of temperature distribution. Some others (such as [6]) are able to achieve an in-plane x−y accuracy slightly higher than our technique; however, this technique is based on the measurement of the optical phonon frequency of the GaN layer, and thus, it provides an averaged temperature information across the transversal growth direction due to the optical response of all the bulk GaN materials to the laser radiation.…”