Kuo-Wei Liu

A self-consistent calculation of the small signal parameters for AlGaAs/GaAs and AlGaAs/InGaAs/GaAs HEMTs

Abstract A detail modeling of the d.c. small-signal parameters for AlGaAs/GaAs HEMTs and AlGaAs/InGaAs/GaAs Pseudomorphic HEMTs (PHEMTs) is presented. The theoretical calculations are based on self-consistent solution of Schrodinger and Poissons equations. Study shows that pseudomorphic HEMTs have a higher transconductance and unity current gain cut-off frequency than those of normal AlGaAs/GaAs HEMTs. In this paper, the calculated transconductances are compared with experimental data and the results show excellent agreement for both devices.

Noise performance of Si/Si/sub 1-x/Ge/sub x/ FETs

Noise characteristics are evaluated for SiGe/Si based n-channel MODFETs and p-channel MOSFETs. The analysis is based on a self-consistent solution of Schrodinger and Poissons equations. The model predicts a superior minimum noise figure for an n-channel MODFET at 77 K. P-channel MOSFETs behave similar to n-channel devices operating at 300 K. Minimum noise figure decreases with increasing quantum well (QW) width for both n- and p-channel devices. However, the p-channel devices are less sensitive to QW width variation. Minimum noise temperature behaves similarly. As observed, a range of doped epilayer thickness exists where minimum noise figure is a minimum for both n- and p-channel FETs. >

Noise temperature modeling of AlGaAs/GaAs and AlGaAs/InGaAs/GaAs HEMTs

Abstract An accurate modeling of noise temperature for AlGaAs/GaAs HEMTs and AlGaAs/InGaAs/GaAs Pseudomorphic HEMTs (PHEMTs) is presented. The analysis is based on a self-consistent solution of Schrodinger and Poissons equations. Pseudomorphic HEMTs have a lower noise temperature as compared to normal AlGaAs/GaAs HEMTs. The minimum noise temperature in pseudomorphic HEMTs decreases with increasing quantum-well (QW) width. Noise temperature in general increases with increasing gate length.

A self-consistent model for small-signal parameters and noise performance of InAlAs/InGaAs/InAlAs/InP HEMTs

An analytical model to evaluate device’s quantum well (QW) properties, current–voltage (I–V) characteristics, smallsignal parameters and noise property for InAlAs/InGaAs/InAlAs/InP high electron mobility transistors is presented.A self-consistent solution of Schr€ and Poisson’s equations is used to calculate the QW properties formed in the InGaAs layer (conduction channel) as well as an analytical velocity–electric field (vd–E) characteristics to evaluate device’s I–V characteristics, small-signal parameters and noise performance.In this paper, the calculation results of device performance for this class of devices are compared with experimental data and the results show good agreement.

DC, small‐signal parameters and noise performance for SiGe/Si FETs

An analytical model to evaluate d.c. small signal parameters and noise performance for the SiGe/Si based FETs is presented, that is based on a self‐consistent solution of Schrodinger and Poisson’s equations and an improved velocity‐electric field (vd−e) characteristics. The presence of a self‐consistent calculation provides a better insight in the dependence of the device parameters on the QW properties. Moreover, the inclusion of a modified velocity‐electric field characteristic enables us to calculate small‐signal parameters that are in excellent agreement with experimental data both at 300 K and 77 K, respectively. The theoretical calculation of noise properties for SiGe/Si based FETs are presented.

An analytical model of small-signal parameters for GaAs/AlGaAs inverted high electron mobility transistors

An analytical model to calculate the small-signal parameters for GaAs/AlGaAs inverted high electron mobility transistors is presented. The model is based on a self-consistent solution of the Schrodinger and Poissons equations and non-linear velocity–electric field (vd−E) characteristic to evaluate the small-signal parameters for this class of devices. These include transconductance gm, drain resistance rd, gate-source capacitance Cgs and unity current gain cut-off frequency fT. The analytical results are compared with the experimental data and show excellent agreement.

An analytical characterization for IMODFETs

A model to calculate the small-signal parameters of GaAs/AlGaAs inverted MODFET (I-MODFET) is presented. The model is based on a self-consistent solution of the Schroedinger and Poissons equations. A non-linear velocity-electric field (V/sub d/-E) characteristic is used to evaluate the small-signal parameters for this class of devices. These include the transconductance g/sub m/, the drain resistance r/sub d/, the gate-source capacitance C/sub gs/ and the unity current gain cut-off frequency f/sub T/. The analytical results are compared with the experimental data and show excellent agreement.

Noise in Si / Si1-xGex n-channel HEMTs and p-channel FETs

A theoretical model to evaluate noise in SiGe/Si based n-channel MODFETs and p-channel MOSFETs is presented. The analysis is based on a self-consistent solution of Schrodinger and Poisson’s equations. In this study, n-channel FETs exhibit a better noise performance than that of p-channel FETs. The influence of device parameters on noise properties for this class of devices are presented.

Study of localization using quantum-mechanical tunneling time and modeling of shot noise

Tunneling time is used to study localization in a quasi-1D system in the presence of random elastic scattering. Schrodinger and Poissons equation are solved self-consistently to calculate the developed space charge. The self-consistently calculated tunneling time is used to calculate shot noise in such structures.