Optical study of high-biased AlGaN/GaN high-electron-mobility transistors

Abstract

Microscopic electroluminescence (EL) and photoluminescence (PL) measurements of high-biased AlGaN/GaN high-electron-mobility transistors are reported. We observed that the EL intensity reveals peaks around the edge of the channel and the electron temperature there is higher than the electron temperature at the center of the channel. These EL features were found to be consistent with the change in the junction temperature, which we locally estimated by comparing the PL data with measurements in raised ambient temperatures.

Fluctuation technique for investigation of ultrafast processes

“…According to Monte Carlo simulation, the mentioned quasi-equilibrium supports a useful approximate equality, T n ≈ T e , valid for a 2D channel located in GaN within several percent [25]. Figure 1 illustrates that the electron temperature estimated from the noise experiment [6] is in a satisfactory agreement with the available independent optical data [26,27].…”

“…1. Dependence of excess electron temperature Te − T0 on supplied electric power (per electron) for GaN-based channels estimated from noise (circles [6]) and optical spectra (horizontal bar [26], squares [27]). …”

Solid immersion lenses for enhancing the optical resolution of thermal and electroluminescence mapping of GaN-on-SiC transistors

“…[ 3,4,6,11,15 ] and Refs. [ 7,9,17 ], respectively. All measurements were performed at an ambient temperature of 22°C.…”

“…Three dimensional temperature mapping has enabled the effect of thermal boundary resistance on heat flow across the interface between heteroepitaxial layers and substrates to be quantified in GaN HEMTs. 11,12 Hot electron electroluminescence also generated by the presence of the high electric field region can also be studied optically: both location of high electric and electron temperature can be obtained by measuring the emitted light, 7 and the breakdown location in devices subjected to electrical stress. 8,9 Although these techniques do offer comparatively high spatial resolution, in particular when compared to electrical measurement techniques which measure a spatial average over the whole device periphery, even more information could be gained by further enhancing spatial resolution.…”

“…3 Therefore, suitable measurement techniques should have a sufficiently high spatial resolution to ensure that that these effects are not underestimated due to spatial averaging. Microscopy based optical measurement techniques, including Raman thermography (measuring lattice temperature, 4 strain, 5,6 electric field 3 ) and electroluminescence emission (measuring hot carriers 7 and leakage pathways 8,9 ), have been used extensively to analyze AlGaN GaN HEMTs.…”