A physical large-signal model for GaN HEMTs including self-heating and trap-related dispersion

We show results of a self-consistent large-signal electro-thermal GaN HEMT model that includes trap related and self-heating dispersion effects. Both self-heating and trap dynamics are treated with a strictly physical approach that makes it easier to link the model parameter with the physical HEMT structure and material characteristics. The model, implemented in ADS, is applied to measured DC data taken at ambient temperatures between 200 K and 400 K, with excellent results. Several examples are given of dynamic HEMT simulation, showing the co-existence and the interaction of temperature- and trap related dispersive effects

Thermal broadening of two-dimensional electron gas mobility distribution in AlGaN/AlN/GaN heterostructures

Two-dimensional electron gas (2DEG) transport in Al0.3Ga0.7N/AlN/GaN heterostructures has been studied using magnetic-field dependent Hall-effect measurements and advanced mobility spectrum analysis techniques over the temperature range from 95 K to 300 K. It is shown that electronic transport is due to a single well-defined 2DEG species, with room-temperature sheet concentration and average mobility of 9.3×1012 cm-2 and 1,880 cm2/Vs, respectively. No parasitic conduction through the bulk GaN layer was detected. Importantly, it is shown that the 2DEG exhibits an approximately Gaussian mobility distribution, the linewidth of which broadens with increasing temperature. This is the first reported observation of thermal broadening effects in the 2DEG mobility distribution

Ion versus pH sensitivity of ungated AlGaN/GaN heterostructure-based devices

We have investigated the pH and ion sensitivity of AlGaN/GaN heterostructure devices; these devices are sensitive to the ion concentration rather than to the pH of the solution. Sheet resistance as a function of pH for calibrated pH solutions and dilute NaOH, HCl, KOH, and NaCl showed an increase as a function of ionic concentration, regardless of whether the pH was acidic, basic, or neutral. An increase in resistance corresponds to accumulation of negative ions at the AlGaN surface, indicating device selectivity toward the negative ions. We attribute this to the formation of a double layer at the liquid/semiconductor interface