Extrinsic Performance Limitations of AlGaN/GaN Heterostructure Field Effect Transistors

Abstract

Extrinsic effects on the DC output characteristics of AlGaN/GaN HFETs with 1 m gate lengths are examined. The devices investigated were fabricated on MOCVD-grown AlGaN/ GaN heterostructures on sapphire substrates. An analytical model that takes into account parasitic resistances and thermal effects is constructed, and its results are compared with experimental data. With parameters determined from characterization experiments on the same wafer and from independent theoretical results, the agreement between the data and the model predictions is found to be very good. The model is then applied to performance predictions for devices with improved series resistances and heat sinking.

Scattering analysis of 2DEG carrier extracted by QMSA in undoped Al0.25Ga0.75N/GaN heterostructures

“…HEMTs based on Al x Ga 1−x N/GaN heterostructures are the most interesting candidate since their description in 1993 [1] and demonstration of high-power operability [2]. Due to their large bandgap energy, large electron drift velocities, high conduction band discontinuity and high thermal stability, Al x Ga 1−x N/GaN heterostructures can operate at high power and high temperature conditions with a 2DEG density and high mobility values as compared even with GaAs-based devices [3][4][5][6].…”

Electro-thermal modeling of multifinger AlGaN/GaN HEMT device operation including thermal substrate effects

“…Thermal modeling circumvents some of these issues. Several efforts have modeled the device and substrate with the assumption that the thermal dissipation can be modeled as a constant power emitter of some characteristic length and width along the gate edge [7][8][9], and other efforts have modeled the two-dimensional thermal profile within the HEMT to gain a better understanding of local variations [10,11]. In this work, we couple an electro-thermal model of HEMT operation with a three-dimensional thermal model of the substrate.…”

Comprehensive analysis of small-signal parameters of fully strained and partially relaxed high Al-content lattice mismatched Al/sub m/Ga/sub 1-m/N/GaN HEMTs

“…The drain current ( ) is obtained from current density equation as (6) where is the gatewidth, is the Boltzmann constant, is the temperature, and is the field-dependent electron mobility given [35] and [40] as (7) where is the low-field mobility, is the critical electric field, and is the saturation drift velocity of the electron. Using (1) and (7) in (6), we obtain (8) where Integrating (8) with boundary conditions…”