Effects of Self-Heating on Performance Degradation in AlGaN/GaN-Based Devices

A self-consistent electrothermal transport model that couples electrical and thermal transport equations is established and applied to AlGaN/GaN device structures grown on the following three different substrate materials: 1) SiC; 2) Si; and 3) sapphire. Both the resultant I-V characteristics and surface temperatures are compared to experimental I -V measurements and Raman spectroscopy temperature measurements. The very consistent agreement between measurements and simulations confirms the validity of the model and its numerical rendition. The results explain why the current saturation in measured I-V characteristics occurs at a much lower electric field than that for the saturation of electron drift velocity. The marked difference in saturated current levels for AlGaN/GaN structures on SiC, Si, and sapphire substrates is directly related to the different self-heating levels that resulted from the different biasing conditions and the distinctive substrate materials.     

Random dopant related variability in the 30 nm gate length In<Subscript>0.75</Subscript>Ga<Subscript>0.25</Subscript>As implant free MOSFET

Implant free MOSFETs take advantage of the high mobility in III–V materials to allow operation at very high speed and low power. However, as with conventional silicon devices, they will be susceptible to intrinsic parameter fluctuations due to random discrete doping. In this paper, we investigate the impact of random discrete dopants induced fluctuations in the δ-doping layer on the threshold voltage of the 30 nm gate length implant free III–V MOSFET.     

Statistical study of the effect of interface charge fluctuations in HEMTs using a 3D simulator

The intrinsic parameter fluctuations associated with the discreteness of charge and matter become an important factor when the semiconductor devices are scaled to nanometre dimensions. The interface charge in the recess regions of high electron mobility transistors (HEMTs) has a considerable effect on the overall device performance. We have employed a 3D parallel drift-diffusion device simulator to study the impact of interface charge fluctuations on the I-V characteristics of nanometre HEMTs. For this purpose, two devices have been analysed, a 120 nm gate length pseudomorphic HEMT with an In_0.2Ga_0.8As channel and a 50 nm gate length InP HEMT with an In_0.7Ga_0.3As channel.     

Atomistic effect of delta doping layer in a 50 nm InP HEMT

Fluctuations caused by discreteness of charge will play an important role when devices are scaled to gate lengths approaching nanometer dimensions. In this paper, we use a 3D drift-diffusion simulator to study an influence of discrete random dopant charges in the delta doping layer of a 50 nm gate length InP high electron mobility transistor.     

Quantum Corrections in the Monte Carlo Simulations of Scaled PHEMTs with Multiple Delta Doping

The effective potential approach which can represent quantum mechanical (QM) confinement at a heterointerface has been incorporated into our Monte Carlo device simulator MC/H2F. The simulator is used to investigate the impact of the quantum corrections on the performance of single and double -doped pseudomorphic high electron mobility transistors scaled to decanano dimensions. The QM confinement in the device channel results in reduction of the drive current and the device transconductance. Its influence increases with the device scaling from 120 to 30 nm gate length and also with increasing the carrier sheet density in the double -doped structures.     

Tetrahedral elements in self-consistent parallel 3D Monte Carlo simulations of MOSFETs

Novel thin-body architectures with complex geometry are becoming of large interest because they are expected to deliver the ITRS prescribed on-current when semiconductor transistors are scaled into nanometer dimensions. We report on the development of a 3D parallel Monte Carlo simulator coupled to a finite element solver for the Poisson equation in order to correctly describe the complex domains of advanced FinFET transistors. We study issues such as charge assignment, field calculation, treatment of contacts and parallelisation approach which have to be taken into account when using tetrahedral elements. The applicability of the simulator is demonstrated by modelling a 10 nm gate length double gate MOSFET with a body thickness of 6.1 nm.