A high-current pseudomorphic AlGaAs/InGaAs double quantum-well MODFET

Double-side planar-doped AlGaAs/InGaAs/AlGaAs MODFET with current density of 1 A/mm

“…This was done by leaving two quantum wells under the gate which in addition were highly doped. Wang et al [4] used a two-quantum-well pseudomorphic structure and achieved an even slightly higher current density of 1.1 A/mm for a 0.3-pm device but at the expense of high-frequency performance. They obtained cutoff frequencies of fT = 52 GHz and fc = 110 GHz with a 0.3-pm gate length.…”

Crossover from negative to positive magnetoresistance in the double quantum well system with different starting disorder

“…Since the DQW has two 2DEGs occupying the lowest subbands in their respective quantum wells, it offers a suitable platform to study the comparative strength of scattering between the subbands with the long and short range scattering potentials. Moreover, from the application point of view, the importance of this study can be gauged from the fact that the heterostructures based on the DQW system forms the important building block for designing the novel optical and electrical devices such as quantum cascade lasers, terahertz generators, variable mobility transistors and high power field effect devices [7][8][9][10]. Therefore it is of primary importance to understand the role of different scattering mechanisms in the DQW heterostructures to optimize the performance of these devices.…”

Intrinsically Linear Transistor for Millimeter-Wave Low Noise Amplifiers

“…The output current of an amplifier is fundamentally related to the input voltage signal by a nonlinear transconductance, g m , whose higher order terms lead to intermodulation products with frequencies close to that of the fundamental signal, thereby invading the bandwidth of the amplifier and draining its available power. , Conventional transistors have a bell-shaped g m curve as a function of V G that is attributed to several physical origins including (i) self-heating effects, (ii) increase of the dynamic source access resistance, (iii) emission of optical phonons, and (iv) contact barriers . Transistors with vertically stacked multiple quantum well channels were hypothesized to lower g m nonlinearities, , but these were not practically utilized. Innovative material approaches including the use of nitrogen-polar surfaces on gallium nitride (GaN) and source regrowth advanced the linearity figure of merit, the ratio of output third-order intermodulation intercept point (OIP3) to DC power ( P DC ), OIP3/ P DC , to 13.3 dB. − The limited transistor linearity is often addressed with circuit linearization techniques employing derivative superposition (DS) − and cancellation that can extend transistor linearity at low frequencies but become difficult to implement at high frequencies and cannot handle signals with sufficiently large power …”

“…1,2 Conventional transistors have a bell-shaped g m curve as a function of V G that is attributed to several physical origins including (i) selfheating effects, 3 (ii) increase of the dynamic source access resistance, 4 (iii) emission of optical phonons, 5 and (iv) contact barriers. 6 Transistors with vertically stacked multiple quantum well channels were hypothesized to lower g m nonlinearities, 7,8 but these were not practically utilized. Innovative material approaches 9 including the use of nitrogen-polar surfaces on gallium nitride (GaN) and source regrowth advanced the linearity figure of merit, the ratio of output third-order intermodulation intercept point (OIP3) to DC power (P DC ), OIP3/P DC , to 13.3 dB.…”