Full-band Monte Carlo resolution of the Boltzmann transport equation, applied to hot carrier solar cells and ultrafast devices

The aim of this work is the study of charge carriers dynamic under high carrier concentration regimes. The 'Full-Band' Monte Carlo method is used for charge carrier transport/relaxation modeling in III-V semiconductors (GaAs, InAs, GaSb, In_0.53Ga_0.47As and GaAs_0.50Sb_0.50). Electronic band structures are calculated with the Non-Local Empirical Pseudopotential Method which enables the study of ternary alloys within a Virtual Crystal approach. This method has been applied to In_0.53Ga_0.47As and GaAs_0.50Sb_0.50, the latter being a promising material for Heterojunction Bipolar Transistor applications though it lacks experimental characterizations. In highly doped polar semiconductors, the polar optical phonon - plasmon coupling is accounted for via the calculation of the total dielectric function including self-consistent damping parameters. This coupling appeared crucial for the calculation of minority electron mobilities in highly p-doped GaAs, In_0.53Ga_0.47As and GaAs_0.50Sb_0.50. In strongly photo-excited semiconductors, phonon population heating has been included in the study of electrons and holes relaxation. Hot phonon populations, that slow the charge carrier relaxation through the phonon bottleneck effect, have been dealt with a phonon dedicated Monte Carlo model (PhD H. Hamzeh). The study showed that carrier relaxation slowing depends strongly on the photo-excited carrier concentration because of phonon-plasmon coupling in those semiconductors. Charge carrier generation and recombination processes such as photon absorption, radiative recombination, impact ionization and Auger recombinations, have been implemented. The associated generation and recombination rates are directly calculated with the sampled carrier distribution. Thus, the use of coefficients and lifetimes is avoided, and non equilibrium regimes were modeled. Those processes are of prime importance for Hot Carrier Solar Cells optimization. The theoretical photo-current of this kind of 3. generation solar cell with an In_0.53Ga_0.47As absorber have been studied. (author)