The first results of double -channel heterostructures with donor-acceptor doping and systems of alternating thin layers of AlAs/GaAs forming additional digital potential barriers study are presented. It is shown that due to the peculiarities of real space electron transfer in the proposed design, when the surface density of electrons with high mobility is doubled compared to traditional single-channel bilaterally doped heterostructures, even in the absence of digital barriers, the drift velocity overshot does not decrease. The introduction of digital barriers significantly increases the of electrons drift velocity overshot when they fly into the region of a strong field, bringing the drift velocity overshot in the corresponding heterostructures closer to the theoretical limit for the model used – the drift velocity overshot in the undoped bulk material of the channel.

The nonlocal dynamics of electrons in pseudomorphic AlGaAs/GaAs/InGaAs heterostructures with double-sided donor-acceptor doping of AlGaAs barriers and additional digital potential barriers of short-period AlAs/GaAs superlattices around the doped regions has been theoretically studied. For the studied heterostructures, the introduction of digital barriers significantly, by 30–40%, increases the electrons drift velocity overshot when they enter the region of a strong field. The effect of localization of hot electrons on the states in AlAs/GaAs superlattices along the edges of the InGaAs quantum well is revealed. It is shown that taking this effect into account significantly increases the electrons drift velocity overshot, bringing it closer to the maximum theoretical limit for the model used – the drift velocity overshot in the undoped InGaAs bulk material.

The first results of the electrons drift velocity study in inverted AlGaAs/InGaAs/GaAs pseudomorphic heterostructures with donor-acceptor doping and short-period AlAs/GaAs superlattices are presented. It is theoretically shown that the introduction of superlattices significantly, up to one and a half times, increases the electrons drift velocity overshot when they enter the region of a strong field. Localized states in the superlattice between the quantum well and the substrate have been found. It is shown that this effect leads to an additional increase in the electrons drift velocity overshot up to the theoretical limit for the model used, i.e., a drift velocity overshot in the bulk material of the quantum well.

The processes of nonlocal electron heating in transistor heterostructures based on gallium nitride and gallium arsenide were compared. It has been shown that, in the case of GaAs double doped pseudomorphic heterostructures, the real space transfer of electrons significantly reduces their drift velocity overshot in the region of a strong field as compared with pure bulk GaAs, while in GaN-based heterostructures the decrease in the drift velocity overshot does not exceed 30% in the studied cases. Keywords: Real space transfer, field-effect transistor, gain factor

The nonlocal electrons heating in transistor heterostructures based on gallium nitride and arsenide is compared. It is shown that if, in comparison with a pure bulk material, in the case of GaAs double doped pseudomorphic heterostructures, the real space transfer of electrons significantly reduces their drift velocity overshot in the region of a strong field, then for GaN-based heterostructures, the decrease of the drift velocity overshot in the studied cases does not exceed 30%.

The nonlocal dynamics of electrons in pseudomorphic AlGaAs/GaAs/InGaAs heterostructures with double-sided donor-acceptor doping of AlGaAs barriers and additional digital potential barriers of short-period AlAs/GaAs superlattices around the doped regions has been theoretically studied. For the studied heterostructures, the introduction of digital barriers significantly, by 30-40%, increases the electrons drift velocity overshot when they enter the region of a strong field. The effect of localization of hot electrons on the states in AlAs/GaAs superlattices along the edges of the InGaAs quantum well is revealed. It is shown that taking this effect into account significantly increases the electrons drift velocity overshot, bringing it closer to the maximum theoretical limit for the model used --- the drift velocity overshot in the undoped InGaAs bulk material. Keywords: potential barriers, digital barriers, heterostructures, electrons drift velocity overshot.

We report on the results of investigations of the millimeter-wave field-effect transistors with a 0.14‑μm T-shaped gate with pseudomorphic Al0.3Ga0.7As–In0.22Ga0.78As–Al0.3Ga0.7As heterostructures with additional potential barriers based on a two-sided donor–acceptor channel doping. At a frequency of 40 GHz in a wide gate voltage range, the maximum stable gain of more than 15 dB has been obtained. The maximum oscillation frequency of the device is about 250 GHz, the open-channel specific current density is about 0.7 A/mm, and the gate–drain breakdown voltage is 22–31 V for different versions.

The results of millimeter – wave field – effect transistors with a 0.14 µm T – gate on pseudomorphic heterostructures Al0.3Ga0.7As – In0.22Ga0.78As – Al0.3Ga0.7As with additional potential barriers based on two-way donor-acceptor channel doping study are presented. At a frequency of 40 GHz in a wide range of gate voltages, a maximum stable gain of more than 15 dB is achieved. The maximum frequency of the device generation is about 250 GHz, the specific current density at the open channel is about 0.7 A / mm, the breakdown voltage of the gate-drain, depending on the version, is 22 -31 V.

A simple phenomenological model for estimating a drift velocity peak in transistor heterostructures with the strong electron localization in the channel is developed using a self-consistent solution of the Schrödinger and Poisson equations and a system of hydrodynamic equations. It is shown that, when an electron enters the region of a strong field, the donor–acceptor doping increases the average drift velocity of electrons several times in the inverted heterostructures and by a factor of 1.5 in the transistor heterostructures based on the double-sided doped In x Ga 1 – x As–Al y Ga 1 – y As and In x Ga 1 – x As–In y Al 1 – y As heterojunctions. In this case, the surface density of electrons in the double-sided doped structures can be more than doubled without a noticeable deterioration of the transport characteristics.

Abstract: The theoretical estimation of the effect of electron localization in the upper valleys in the narrow-band channel of transistor heterostructures AlxGa1–xAs-GaAs with two-sided doping on the value оf drift velocity overshoot is carried out. It is shown that for transistor heterostructures with donor-acceptor doping, in which the proportion of electrons transferred from the narrow-band channel to the wide-band material is less than in conventional structures, in some cases, the drift velocity increase can reach 15 % due to the localization of electrons in the upper valleys in the narrow-band channel. The studied effect can be an additional mechanism for increasing the current in transistors based on heterostructures with donor-acceptor doping.