Junction temperature

About: Junction temperature is a research topic. Over the lifetime, 5058 publications have been published within this topic receiving 58643 citations.

Enhancement of Hot Spot Cooling by Capped Diamond Layer Deposition for Multifinger AlGaN/GaN HEMTs

Abstract: The impact of a capped diamond layer for enhanced cooling of multifinger AlGaN/GaN high-electron-mobility transistors (HEMTs) has been investigated under the steady-state operating condition. By depositing a capped diamond thin film onto the HEMTs, the temperature distribution around the hot spots tends to be more uniform and the junction temperature can be suppressed significantly. The capped diamond serves as a highly effective heat spreader, and its thermal spreading ability depends on the structural design patterns and working conditions. Some key parameters affecting the thermal performance of the capped diamond have been examined, including the heat dissipation power density, gate pitch distance, embedding depth of the heat source, thermal boundary resistance, substrate material, as well as the cap thickness. For the 12-finger model with 20- $\mu \text{m}$ gate pitch distance and gate power density of 6 W/mm, a 20- $\mu \text{m}$ layer of capped diamond could reduce the junction temperature by 12.1% for GaN-on-diamond HEMTs and by 25.3% for GaN-on-SiC HEMTs. Even with a 1- $\mu \text{m}$ capped diamond layer, the reduction would be 7.6% and 9.9%, respectively. The temperature reduction for GaN-on-Si is more significant.

A step forward in multi-domain modeling of power LEDs

Abstract: Besides their electrical properties the optical parameters of LEDs also depend on junction temperature For this reason thermal characterization and thermal management plays important role in case of power LEDs, necessitating tools both for physical measurements and simulation This paper deals with the combined electrical, thermal and optical characterization and multi-domain modeling of power LEDs The major target is to provide with a model architecture and set of model equations the parameters of which can be all measured using a combined thermal and radiometric and photometric test setup completed with a spectrometer Current and temperature dependent modeling of the light output of white LEDs is also addressed

High Internal Quantum Efficiency Blue-Green Light-Emitting Diode with Small Efficiency Droop Fabricated on Low Dislocation Density GaN Substrate

Abstract: We fabricated blue (~450 nm), blue-green (~500 nm), and green (~525 nm) light-emitting diodes (LEDs) of different dislocation densities (DD) and characterized their internal quantum efficiency (IQE). The IQE of the blue LEDs fabricated using GaN substrate exceeded 90% (DD: ~106 cm-2), however, when we used a GaN-on-sapphire substrate (DD: ~108 cm-2), IQE was limited to ~60%. Droop was reduced by use of the GaN substrate. The junction temperature of the GaN-on-sapphire substrate was found to be ~200 °C although the junction temperature of the GaN substrate was ~50 °C when a forward current of 100 A/cm2 was driven. A lowering of IQE in green LEDs to ~60% was observed, even though we used a low-dislocation-density substrate [DD: (1–2)×107 cm-2]. The junction temperature of blue-green and green LEDs was about 100 °C when a forward current of 177 A/cm2 was driven, which indicated that junction temperature is not a major factor for IQE suppression in green LEDs.

Power generator for vehicle

Abstract: PROBLEM TO BE SOLVED: To improve power generation efficiency by appropriately controlling the temperature of the hot junction of a thermoelectric conversion element in the case of using a thermoelectric conversion that converts exhaust heat into electric energy. SOLUTION: When the temperature of a heat generating member 133 rises and approaches the upper limit of heat resistant temperature of a thermoelectric conversion element 142, a bimetal deforming member 144 is deformed and the radius of curvature becomes small. As a result, a hot junction side heat connecting member 143 is made apart from the member 133 and the mechanical contact between the both is disconnected. For this reason, the heat of the member 133 is not conducted to the member 143 but the temperature rise of the element 142 is limited. COPYRIGHT: (C)2000,JPO

A temperature-dependent electrothermal MOSFET model for calculating its current loadability

Abstract: A developed temperature-dependent electrothermal model consists of a temperature dependent MOSFET model and a temperature independent model of the MOSFET thermal system. The temperature dependent MOSFET parameters are the channel charge carriers mobility, drift area resistance and threshold voltage. Calculated at each moment are voltage, current, losses (including conduction losses, built-in diode losses and switching losses) and the virtual junction temperature. During the simulation, the MOSFET temperature dependent parameters depended on instantaneous virtual junction temperature. The electrothermal model is based on catalog data about MOSFET. It gives the designer highly precise information necessary for electrical and thermal design of electronic circuits, especially of electronic power converters in transient and stationary states. The temperature dependent electrothermal model was developed using an IsSpice4 software program. The existing model of the signal MOSFET was expanded with the temperature dependence of parameters and supplemented with an electrical model of its thermal system. First, the model was checked by simulating catalog characteristics and next by comparing a simulated time course for losses and for virtual junction temperature with a measured time course of losses and virtual junction temperature of the MOSFET in one chopper measuring the time course of virtual junction temperature required designing a special measuring equipment.