Articles you may be interested inSurface photovoltage spectroscopy of metamorphic high electron mobility transistor structures Pseudomorphic high electron mobility transistor structures have been characterized using surface photovoltage spectroscopy and numerical simulations. According to the effect of the electric fields in different regions of the device on the surface photovoltage spectra, a simple empirical model that correlates the spectral parameters and electrical parameters of the structure has been developed. The spectra and their analysis are shown to provide values for the electrical parameters of the structure. The sensitivity of the technique to the device electrical parameters is shown by three different examples. In these examples, the differences in doping level and surface charge have been monitored as well as the nonuniformity of doping level across the wafer.
The calculations of quasistationary Kr and Xe beam-produced plasma parameters were performed in the range of gas densities Na from 1019 up to 1021 cm−3 and ionization degrees Ne/Na from 10−5 up to 10−3. The values of ion and electron densities, populations of excited states and electron temperature Te depending on external ionization rate were obtained in the way of proper balance equation system solving. The main mechanisms responsible for BPP parameters forming were analyzed. Obtained results (specifically, Te from 0.4 up to 0.8 eV) are distinguished with available information in publications.
A systematic study of impact ionization in pseudomorphic high electron mobility transistors (PHEMTs) has been carried out using temperature-dependent electrical measurements as well as modeling for optimizing the power performance of the devices through the best layout parameters. A measurement procedure makes it possible to define a safe transistor operation region is proposed. Impact ionization in the channel is parameterized by specific gate current and voltage values. Temperature-dependent measurements are shown to provide distinction between the impact ionization current and the thermionic field emission current. A methodology for defining an optimum vertical structure and a lateral layout for a given application and operational conditions is developed. Empirical models for optimum lateral layout for a power application were developed based on a statistical "Device Zoo" approach. The results point to an optimal gate-to-drain distance for minimum impact ionization current.Index Terms-Breakdown, empirical models, impact ionization, pseudomorphic high electron mobility transistors (PHEMT).
AlGaN/GaN high electron mobility transistor, AlGaAs/InGAs/GaAs pseudomorphic HEMT, and InAlAs/InGaAs metamorphic HEMT ͑MHEMT͒ epitaxial structures have been characterized using surface photovoltage spectroscopy. The effects of the transistor top and bottom delta-doping levels ␦ top , ␦ bot , and surface charge Q sur on the spectrum features have been studied using numerical simulations. Based on the latter, an empirical model has been developed, which allows extraction and comparison of ␦ top , ␦ bot , and Q sur and is applicable for both double-sided and single-sided delta-doped structures. Prediction of the final device performance by the model is shown for two MHEMT structures. Devices produced on these structures show maximum drain currents, which correlate well with ␦ top values calculated using the model.
Suppression of surface segregation of silicon dopants during molecular beam epitaxy of ( 411 ) A In 0.75 Ga 0.25 As ∕ In 0.52 Al 0.48 As pseudomorphic high electron mobility transistor structures
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