Title :
Modeling of short-pulse threshold voltage shifts due to DX centers in AlxGa1-xAs/GaAs and AlxGa1-x As/InyGa1-yAs MODFET´s
Author :
Chandra, Amitabh ; Foisy, Mark C.
Author_Institution :
AT&T Bell Lab., Murray Hill, NJ, USA
fDate :
6/1/1991 12:00:00 AM
Abstract :
The DX-center-related short-pulse threshold voltage shifts (SPTVS) in AlxGa1-xAs-based MODFETs is modeled using CBAND, a simulator that solves Poisson equations self-consistently with Schrodinger equations and donor statistics. Using values given in the literature for the DX energy level in AlxGa1-xAs this technique gives good agreement between measured and simulated SPTVS for Al0.3Ga0.7As/GaAs and Al0.3Ga0.7As/In0.2Ga0.8As MODFETs. Both simulation and experiment show that the use of Al0.2 Ga0.8As in the donor layer reduces the SPTVS relative to the structures using Al0.3Ga0.7As. However, the measured shifts at this composition are considerably lower than the simulated values, indicating a DX energy level that may be higher than the value extrapolated from the literature, possibly due to the existence of multiple trap levels. Despite this discrepancy, these results support the use of strained-channel layers and lower Alx Ga1-xAs compositions in MODFETs for digital and other large-signal applications requiring good threshold stability
Keywords :
III-V semiconductors; aluminium compounds; gallium arsenide; high electron mobility transistors; indium compounds; semiconductor device models; semiconductor junctions; AlxGa1-xAs-GaAs; AlxGa1-xAs-InyGa1-yAs; CBAND; DX centers; MODFETs; Poisson equations; Schrodinger equations; donor statistics; semiconductors; short-pulse threshold voltage shifts; strained-channel layers; threshold stability; Energy measurement; Energy states; Gallium arsenide; HEMTs; MODFETs; Poisson equations; Schrodinger equation; Stability; Statistics; Threshold voltage;
Journal_Title :
Electron Devices, IEEE Transactions on
