Design, processing and characterization of delta-doped channelAlGaAs/InGaAs/GaAs HFETs

Abstract

We report on design, processing and characterization ofAlGaAs/InGaAs/GaAs HFETs which feature the power capabilities of doubledelta-doped devices and the low noise performance of the standard HFETs. Tostudy the influence of delta doping position on the subband energies and sheetcharge density, numerical simulations based on a self-consistent solution ofPoisson's and Schrödinger's equations have been used for different channelthicknesses. Three different devices with a single δ-doped layerlocated at three different positions inside the channel have been fabricatedand tested. On-wafer noise measurements have revealed that the position of thedelta-doped layer can be optimized to minimize the noise figure without anyrelevant degradation of the maximum transconductance. The device with thedelta-doped layer closer to the bottom heterointerface was found to exhibitthe best performance in terms of the maximum cutoff and maximum oscillationfrequencies and the minimum noise figure.