Transport properties along the channel of a Hemt
In the theoretical modeling of a high electron mobility transistor (HEMT), it is inherently assumed that the variation of quantum confinement along the channel from the source to the drain is about the same and therefore, the transport properties are independent of position and only dependent on the electric field along the channel. In this study, the scattering rates for polar optical phonons (POP), acoustic phonons (AP) through deformation potential and impurity scattering are obtained theoretically based on the Fermi's golden rule as a function of position along the channel for an {dollar}Al\sb{0.37}Ga\sb{0.63}As/GaAs{dollar} HEMT. It is observed that the POP mechanism exhibits a maximum variation of 114% in the scattering rates for both intrasubband and intersubband scattering mechanisms due to varying degrees of quantum confinement from the source to the drain. The AP mechanism shows a maximum variation of 109% and the scattering rate due to impurity scattering presents a maximum variation of 133%. If these wide variations in the scattering rates are not accounted for, in the transport parameter calculation, it will introduce an error in the I-V characteristics, irrespective of the type of device modeling.
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