EFFECT OF APPLIED ELECTRIC FIELD ON ACCEPTOR STATES IN ZINC-BLENDE InGaN/GaN QUANTUM DOT

Based on the effective-mass approximation, the acceptor binding energy in a cylindrical zinc-blende (ZB) InGaN / GaN single quantum dot (QD) is investigated variationally in the presence of the applied electric field. Numerical results show that the acceptor binding energy is highly dependent on the applied electric field, impurity positions and QD size. The applied electric field also induces an asymmetric distribution of the acceptor binding energy with respect to the center of the QD. Moreover, in the presence of the applied electric field, the acceptor binding energy is insensitive to dot height when the impurity is located at the left boundary of the ZB In 0.1 Ga 0.9 N / GaN QD with large dot height (H≥6 nm). In particular, the acceptor binding energy of the impurity located at the left boundary of the ZB In 0.1 Ga 0.9 N / GaN QD is identical for different dot height when the applied electric field F≥350 KV/cm. This result can be of interest for the technological purpose, as it could involve a source of control some impurity-related properties in these systems under the applied electric field.

LTPL Investigation of N-Ga and N-Al Donor-Acceptor Pair Spectra in 3C-SiC Layers Grown by VLS on 6H-SiC Substrates

Ga-doped 3C-SiC layers have been grown on on-axis 6H-SiC (0001) substrates by the VLS technique and investigated by low temperature photoluminescence (LTPL) measurements. On these Ga-doped samples, all experimental spectra collected at 5K were found dominated by strong N-Ga donor-acceptor pair (DAP) transitions and phonon replicas. As expected, the N-Ga DAP zero-phonon line (ZPL) was located at lower energy (~ 86 meV) below the N-Al one. Fitting the transition energies for the N-Al close DAP lines gave 251 meV for the Al acceptor binding energy in 3C-SiC and, by comparison, 337 meV for the Ga acceptor one.