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We present a novel approach to achieve terahertz-range cutoff frequencies and maximum frequencies of operation of GaN based heterostructure field-effect transistors (HFETs) at relatively high drain voltages. Strong short-channel effects limit the frequency of operation and output power in conventional geometry GaN HFETs. In this work, we propose a novel device with two additional independently biased electrodes controlling the electric field and space-charge close to the gate edges. As a result, the effective gate length extension due to short channel effects is diminished and electron velocity in the device channel is increased. Our simulations show that the proposed five-terminal HFET allows achieving fT=1.28 THz and fmax= 0.815 THz at the drain voltages as high as 12 V. Hence, this device opens up a new approach to designing THz transistor sources. [ABSTRACT FROM AUTHOR]

AlGaN thin films and Schottky barrier Al0.4Ga0.6N diodes exhibit generation-recombination (GR) noise with activation energies of 0.8 - 1 eV. GR noise in AlGaN/GaN Heterostructure Field Effect transistors (HFETs) corresponds to activation energies in the range from 1 - 3 meV to 1 eV. No GR noise is observed in thin doped GaN films and GaN MESFETs. GR noise with the largest reported activation energy of 1.6 eV was measured in AlGaN/InGaN/GaN Double Heterostructure Field Effect Transistors (DHFETs). Local levels responsible for the GR noise in HFETs and DHFETs might be located in AlGaN barrier layers. [ABSTRACT FROM AUTHOR]

Describes the properties of novel III-N-based insulating gate heterostructure field-effect transistors (HFET). Metal-oxide-semiconductor heterostructure field-effect transistor (MOSHFETS) fabrication and characteristics; Si[sub 3]N[sub 4]-based insulating gate devices; RF-current collapse in MOSHFETs and MISHFETs.

We report on experimental study of the low frequency noise in GaN-based Field Effect Transistors. In both GaN Metal Semiconductor Field Effect Transistors (MESFETs) and AIGaN/GaN Heterostructure Field Effect Transistors (HFETs), the main noise sources are located in the channel. Gate voltage dependence of noise in MESFETs complies with the Hooge formula and indicates the bulk origin of noise. The dependencies of the Hooge parameter, α; on sheet electron concentration n[sub s] in HFETs are extracted from measured drain current fluctuations taking into account the contact resistance, and the resistance of the ungated regions of the transistors. At low channel concentrations α is inversely proportional to n[sub s] (α ∼1/n[sub s]). This dependence as well as the temperature dependence of noise might be explained by electron tunneling from the 2D gas into the traps in the bulk GaN or A1GaN. [ABSTRACT FROM AUTHOR]

We report on the first metal-oxide-semiconductor AIGaN/GaN radio-frequency (RF) switch with capacitively coupled contacts using a HfO2 layer as the gate dielectric and surface passivation layer. The new insulating-gate RF switch has a lower leakage current and can handle higher RF powers than A1GaN/GaN HFET switches. [ABSTRACT FROM AUTHOR]