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The shift of resonance energy in direct optical interband transitions is evaluated. The case of hole transitions between heavy and light mass valence bands is considered, using the full form of the Luttinger-Kohn Hamiltonian. In addition to anisotropy, very large Bloch-Siegert shift, of the order of 100%, was found at high IR light intensities in the teraherz frequency range. The shift is related to a periodic hole motion in the Brillouin zone.

Experimental studies on shallow acceptor and donor field ionization dynamics in MBE-grown GaAs epitaxial layers are presented. The experiments have been carried out with a new non-resonant spectroscopic technique, transient tunnelling spectroscopy. It has been found that intense hole tunnelling from shallow acceptors begins at electric fields higher than 6000 V cm-1, while electron tunnelling from shallow compensating donors to the conduction band occurs at much lower electric fields, of the order of 500 V cm-1. The dependence of the acceptor to valence band tunnelling time on the electric field strength has been measured for the first time, From the analysis of the experimental results it is concluded that initially the acceptor to valence band tunnelling dynamics is dominated by a light-hole mass.

We present experimental results on the field ionization of beryllium acceptors in micrometre AlGaAs/GaAs structures on a nanosecond timescale. At liquid helium temperature, the tunnelling ionization of beryllium was found to switch on effectively at electric fields higher than .

For pt.I see ibid., vol.1, no.48, p.9637 (1989). The Monte Carlo method described in paper I is used to find heavy- and light-hole distribution functions and inter-valence absorption cross sections at high infrared laser intensities. At such intensities a hole is burned out in the hole distribution function and, as a result, the p-type semiconductor becomes transparent. The graphs of inter-valence absorption cross sections as a function of NH3 and CO2 laser electric field strength inside the semiconductor are presented for p-type germanium at two lattice temperatures, T=300 and 77 K and compared with the available experimental results. The paper also demonstrates how the Monte Carlo method can be extended to include valence band warping and non-parabolicity.

This is the first of two papers that present general principles of Monte Carlo (MC) simulation of linear and non-linear infrared-radiation absorption due to hole inter-valence transitions in p-type semiconductors. In the MC model the heavy- and light-mass sub-bands are treated as a collection of two-level systems, wherein the hole due to excitations by lattice vibrations hops between different members of the system. The close analogy with the two-level system allows one to incorporate into the MC program such purely quantum-mechanical effects as Rabi oscillations and dephasing. In this paper the general principles are presented and used to calculate absorption cross section at weak laser intensities. High-intensity absorption will be treated in the second paper.