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A study was conducted to simulate the strained silicon channel SiGe n-modulation doped field effect transistor (n-MODFET) structure by a one-dimensional self-consistent Schroedinger-Poisson charge control framework. The heterojunction interfaces were assumed to be free of interface charge while the exchange correlation effects were determined to be negligible for conduction band computations. Results indicated that the higher Ge mole fraction in the SiGe adjacent to channel layers supported the frequency performance of the n-MODFET.

Reflection-type structures are investigated in fragment rotational state distributions following the decay of long-lived resonances with k*=0–2 quanta of bending vibration of the intermediate complex. The calculations are performed in relation to the photodissociation of ClNO(T1). In the absence of an ab initio potential energy surface we construct a model potential energy surface which reproduces some of the main features of this system in qualitative agreement with experimental data. In particular, excitation of the lowest bending state of the ClNO(T1) complex yields a Gaussian rotational distribution while excitation of the first two excited bending states gives rise to bi- and trinodal distributions, respectively. Employing a simple classical model demonstrates that the structures of the final distributions can be explained as a mapping of the corresponding wave function along the transition line which separates the complex region from the exit channel. Within this model the final fragmentation step will be treated as direct dissociation which starts at the transition state with the quantum mechanical coordinate distribution serving for the weighting function. In order to illustrate the sensitivity of the rotational NO distributions we carry out calculations for three potentials with different anisotropy in the exit channel. [ABSTRACT FROM AUTHOR]

An ab initio study of the photodissociation of ClNO following excitation of the T1 state is presented. The corresponding three-dimensional potential-energy surface has been calculated using extensive complete-active-space self-consistent-field (CASSCF) and multireference-averaged coupled pair functional (MR-ACPF) wave functions and large basis sets. The nuclear dynamics has been treated by solving the time-dependent Schrödinger equation in three dimensions. The steepness of the potential with respect to the dissociation coordinate in the Franck–Condon region is found to be very crucial for a realistic description of the dissociation dynamics. It controls directly the lifetime of the ClNO(T1) complex and therefore the widths of the vibrational structures in the absorption spectrum. Due to very large dynamical electron correlation effects, the CASSCF potential is found to be much too steep. Even with extended MR-ACPF wave functions an empirical scaling of the correlation energy is necessary in order to obtain a potential which is sufficiently flat in the transition region to allow for the splitting of each vibrational band into three bending peaks. Only the absorption spectrum calculated with the scaled MR-ACPF potential is in very good agreement with the measured spectrum. The dissociation proceeds adiabatically as far as the vibrational degree of freedom of NO is concerned with the result that excitation of ClNO(T1) within vibrational band n* yields almost exclusively products NO(n*). The degree of rotational excitation of the NO fragment is relatively low, i.e., the distributions peak at low rotational quantum numbers. The calculations reproduce the intriguing relation between the bending state in the ClNO(T1) complex (k*) and the multimodal structures in the final rotational-state distributions, first observed experimentally by Reisler and co-workers [J. Chem. Phys. 89, 6547 (1988)]. [ABSTRACT FROM AUTHOR]