We report on comparison studies between a novel transistor-like device and two dimensional Fin Field-effect transistor (2DEG FinFET) towards their applications in a THz resonant detector. Both device structures have been fabricated on the same wafer of GaN/AlGaN epistructure during one processing run. The proposed here the transistor-like structure has two side Schottky gates, which can be biased towards complete pinch-off the 2DEG channel in this device. The characteristic dimensions of all device structures are in the range of typical for the laser writer processing i.e. a few micrometers, however in the case of the transistor-like device we report on electronical tuned confinement, which works down to submicron range. At certain conditions, near to pinch-off region, it is possible to obtain one dimensional current flow. This feature is especially attractive for THz resonant detector approach, which will be discussed in details.

We report on a design of fin-shaped channel GaN/AlGaN field-effect transistors developed for studying resonant terahertz plasma oscillations. Unlike common two dimensional FinFET transistor design, the gates were deposited only to the sides of the two dimensional electron gas channel, i.e., metal layers were not deposited on the top of the AlGaN. This side gate configuration allowed us to electrically control the conductivity of the channel by changing its width while keeping the carrier density and mobility virtually unchanged. Computer simulations and analytical model describe well the general shape of the characteristics. The side gate control of the channel width of these transistors allowed us to eliminate the so-called oblique plasma wave modes and paves the way towards future terahertz detectors and emitters using high quality factor plasma wave resonances.

A method to compensate the field effect transistor (FET) channel third-order nonlinearity is proposed and experimentally demonstrated. The FET channel current-voltage (I-V) characteristic is sublinear and hence the related nonlinearity can be compensated by adding the component with superlinear I-V. Such I-V can be realised by using Schottky-type contacts to the FET channel or by connecting the FET to external Schottky diodes. In this reported work, the criterion for nonlinearity compensation is derived. Next, as a proof of concept, a discrete prototype circuit containing a MOSFET and compensating circuit has been designed, built and tested. As confirmed by two-tone measurements, reduction of third-order distortions up to 26 dBm has been achieved by using the nonlinearity compensation network.

We report on millimeter wave electromagnetic radiation from a GaN high electron mobility transistor with the gate length of 1.5 μm at 8 K. The emission takes place at gate and drain voltages in the linear regime of operation but close to the saturation voltage with the principal emission peak at approximately 75 GHz, which is much higher than the device cut-off frequency. An explanation of this effect involves the “shallow water” plasma wave instability, with the frequency of the plasma waves decreased by the ungated regions of the device.

An advantage for some wide bandgap materials, that is often overlooked, is that the thermal coefficient of expansion (CTE) is better matched to the ceramics in use for packaging technology. It is shown that the optimal choice for uni-polar devices is clearly GaN. It is further shown that the future optimal choice for bipolar devices is C (diamond) owing to the large bandgap, high thermal conductivity, and large electron and hole mobilities. A new expression relating the critical electric field for breakdown in abrupt junctions to the material bandgap energy is derived and is further used to derive new expressions for specific on-resistance in power semiconductor devices. These new expressions are compared to the previous literature and the efficacy of specific power devices, such as heterojunction MOSFETs, using GaN are discussed.

Simple analytical approximation has been obtained to describe the temperature and concentration dependencies of the low-field mobility in gallium nitride (GaN) in wide temperature (50⩽T⩽1000 K) and concentration (1014⩽N⩽1019 cm−3) ranges. The dependence of the temperature Tm at which the mobility μ is at a maximum on the doping level is also obtained. Results obtained can be directly used for computer simulation of GaN-based devices.

An advantage for some wide bandgap materials, that is often overlooked, is that the thermal coefficient of expansion (CTE) is better matched to the ceramics in use for packaging technology. It is shown that the optimal choice for uni-polar devices is clearly GaN. It is further shown that the future optimal choice for bipolar devices is C (diamond). A new expression relating the critical electric field for breakdown in abrupt junctions to the material bandgap energy is derived and is further used to derive new expressions for specific on-resistance in power semiconductor devices. These new expressions are compared to the previous literature and the efficacy of specific power devices, such as heterojunction MOSFETs, using GaN are discussed

In this paper the high frequency behavior of integrated pn- photodiodes is discussed and measurement results of two different types of photodiodes, one implemented in a standard 1.2 micrometers BiCMOS process and the other in a 0.8 micrometers CMOS process are presented. The rise times and responsivities of the photodiodes are under 5 ns and 0.26 A/W in the CMOS process and about 30 ns and 0.23 A/W in the BiCMOS process, respectively. Furthermore, the suitability of the technique for 3D vision has been investigated by designing an array of photodetectors and measuring the isolation between detector blocks.

Two algorithms for synchronization of a pair of autonomous tunnel-diode generators of chaotic oscillations (a receiver and a transmitter) that are efficient for the unknown (or known not exactly) transmitter parameters are proposed and investigated.

Low frequency noise in 4H-silicon carbide junction field effect transistors (JFETs) has been investigated. JFETs with a buried p+n junction gate were manufactured by CREE Research Inc. Very low noise level has been observed in the JFETs. At 300 K the value of Hooge constant α is as small as α∼10−5 and the α value can be decreased by an appropriate annealing to α∼2×10−6. It has been shown that even these extremely low noise values are determined not by the volume noise sources but by the noise at the SiC–SiO2 interface.

Two synchronization algorithms for a pair of semiconductor chaotic generators (transmitter and receiver) are proposed. It is shown, that both of them are efficient under uncertainty of parameters of the transmitter. Computer simulation results are presented confirming the theoretical analysis.

Low frequency noise in the two-dimensional metal-semiconductor field effect transistor (2D-MESFET) is reported. It is shown that the noise level S is rather small. At room temperature the value of Hooge constant α was about 2×10−5 for frequency f=20 Hz. The frequency dependence of the relative spectral density of current fluctuations SI/I2 at 300 K was close to S∼1/f0.6 in the frequency range 20 Hz–20 kHz. Two local maxima were observed in the temperature dependence of S in the ranges 100–180 K and 200–300 K.

A simple analytical method to determine the maximum field, outside field and excess voltage of a stable domain is put forward for any values of the carrier concentration, sample length and bias. This method provides good agreement with the exact solutions, for both stable-domain and transient processes in Gunn diodes.