Simulation of Thermal Effects on Hydrogen-Terminated Diamond MOSFETs

Abstract

The DC characteristics of hydrogen-terminated diamond (HTD) MOSFETs are simulated in the temperature range from 140 to 500K. The temperature-dependent parameters, such as band gap width, intrinsic/extrinsic carrier density, hole mobility and hole saturation velocity, are calculated and compared with measured data. The simulated output/transfer characteristics show good agreement with experiments, and the maximum drain current shows smaller thermal variation than the low-field mobility does, which is due to the existence of transverse field during device operation. In addition, the pinch-off voltage is found to change linearly with temperature and the temperature coefficient is as small as 0.26mV/K. The thermodynamic simulation reveals that for HTD MOSFETs, the lattice temperature will increase only 30K when the device is operated at a current density as high as 1A/mm.

Gate-Source Distance Scaling Effects in H-Terminated Diamond MESFETs

“…Conversely, the downscaling of L GD does not produce any increase in the electric field in the source-gate region, thus not affecting the saturated drain current. On the basis of [25], a similar behavior should be expected for H-terminated diamond devices. In [25], in more detail, the threshold fields for the onset of the nonlinear carrier velocity regime are shown, both for bulk and surface holes.…”

“…On the basis of [25], a similar behavior should be expected for H-terminated diamond devices. In [25], in more detail, the threshold fields for the onset of the nonlinear carrier velocity regime are shown, both for bulk and surface holes. Threshold values in the range 10-100 kV/cm have been reported, where the lower bound is associated with bulk holes and a low level of impurities per volume, whereas the upper bound is associated with bulk holes and a high level of impurities per volume or, equivalently, with superficial holes in the 2-DHG.…”

“…As a consequence, it is not possible to establish with sufficient confidence what effect originates the observed double hump: this topic may deserve further investigation on the basis of advanced physical simulations. At any rate, physical models presented so far in [25], [32], and [33] are not suited to predict the observed transconductance humps.…”

“…In the references above, the current density increase in the active channel associated to a reduction of the gate-source distance is shown to be due to the peculiar velocity-field characteristics of GaN or SiC semiconductors, in which the ohmic (linear) regime extends up to electric fields in the order of 100 kV/cm [23], [24]. Such a physical property can be transposed to diamond devices, characterized by saturation electric fields [25] close to the values reported for GaN and SiC. To the best of the authors' knowledge, such study has not been performed yet on H-terminated diamond MESFETs.…”

A New Capacitance-Voltage Model for Hydrogen-Terminated Diamond Mosfet

“…Then a set of differential equations that describe the device physics will be solved at each grid, and the device properties between any two grids will be derived through interpolation (5). The values of material parameters for HTD used in simulation are listed in table I (6,7).…”