as low as 120 nm.
For pseudomorphic high power devices, especially for the Ka-frequency band, predictive
simulation studies are performed for large scale processes. The development is supported by active
load-pull measurements. Special emphasis was paid to the investigation of statistical process
variations with respect to the device optimization.
For simulation of AlGaN/GaN HEMTs material models have been developed and first
simulations have been performed, which show good agreement with measurements.
For the future of process development, pseudomorphic HEMTs will strongly compete with
the silicon based RF-devices. A major issue of further development will be process simplification
and stabilization in order to reduce costs while preserving or even improving device performance.
Metamorphic HEMTs for industrial processes are under development for low noise and high
gain amplifiers. High-speed InAlAs/InGaAs HEMTs for data rates of 80 Gbit/s and beyond are being
developed for the next generation optical data transmission. For sensing applications at and
beyond 94 GHz, i.e., in the next atmospheric windows at 140 GHz and 220 GHz, reliable low noise and
power processes with gate-lengths below
100 nm are to be developed.
Possible directions for improvement of GaAs based III-V device simulation are the
understanding of breakdown considering dynamic trap occupation. These dynamic issues of breakdown
need to be addressed similarly to approaches for silicon, e.g. for electrostatic discharge.
Further modeling of the III-V quaternary materials is required for InAlGaAs, InGaAsP, and
AlGaAsSb. More knowledge is required for the understanding of the process influence on the
SiN/barrier interface.
For GaN based HEMTs more specific high field models need to be developed for the
hydrodynamic transport based on MC models and improved material characterization.
Spontaneous and piezoelectric polarization effects require further understanding. This includes
scattering at the channel interfaces, in AlGaN barrier layers, and the metal-semiconductor
contacts. The high field mechanisms for transport in the AlGaN/GaN barrier layers need to be
understood in order to control and stabilize the resistances
and
. The impact of
surface passivation requires further investigation.
For ultra high-speed low power
devices the development of simulation tools for InP based HBTs and InAs/AlSb HEMTs is required.
Furthermore, the simulation of S-parameters for the HBTs with InGaP/GaAs needs to be
further developed. For InP based HBTs the existing model base needs to be applied parallel to the
continuing process development.
More computationally efficient three-dimensional electro-thermal device simulators will
lead to a closer connection towards chip design, especially when thermal effects are addressed.
Although a variety of simulators have successfully demonstrated formidable agreement with measurements, the understanding of changes of transport and interface parameters due to the influence of specific process steps remains the ultimate goal of process control.