Splitting of type-I (N-B, P-Al) and type-II (N-Al, N-Ga) donor-acceptor pair spectra in 3C-SiC

Discrete series of lines have been observed for many years in donor-acceptor pair (DAP) spectra in 3C-SiC. In this work, the splitting of both type-I (N-B, P-Al) and type-II (N-Al, N-Ga) DAP spectra in 3C-SiC has been systematically investigated by considering the multipole terms. For type-I spectra, in which either N or B substitutes on C sites or P and Al replace Si, the splitting energy of the substructure for a given shell is almost the same for both pairs. For type-II spectra, in which N is on the C site while Al and Ga acceptors replace Si, we find that, when compared with literature data, the splitting energy for a given shell is almost independent of the identity of the acceptor. For both type-I and type-II spectra, this splitting energy can be successfully explained by the octupole term V-3 alone with k(3)=-2x10(5) angstrom(4) meV. Comparing the experimental donor and acceptor binding energies with the values calculated by the effective-mass model, this suggests that the shallow donor (N, P) ions can be treated as point charges while the charge distribution of the acceptor ions (Al, Ga, B) is distorted in accord with the T-d point group symmetry, resulting in a considerable value for k(3). This gives a reasonable explanation for the observed splitting energies for both type-I and type-II DAP spectra.Original Publication:J W Sun, Ivan Gueorguiev Ivanov, S Juillaguet and J Camassel, Splitting of type-I (N-B, P-Al) and type-II (N-Al, N-Ga) donor-acceptor pair spectra in 3C-SiC, 2011, PHYSICAL REVIEW B, (83), 19, 195201.http://dx.doi.org/10.1103/PhysRevB.83.195201Copyright: American Physical Societyhttp://www.aps.org

Splitting of type-I (N-B, P-Al) and type-II (N-Al, N-Ga) donor-acceptor pair spectra in 3C-SiC

Discrete series of lines have been observed for many years in donor-acceptor pair (DAP) spectra in 3C-SiC. In this work, the splitting of both type-I (N-B, P-Al) and type-II (N-Al, N-Ga) DAP spectra in 3C-SiC has been systematically investigated by considering the multipole terms. For type-I spectra, in which either N or B substitutes on C sites or P and Al replace Si, the splitting energy of the substructure for a given shell is almost the same for both pairs. For type-II spectra, in which N is on the C site while Al and Ga acceptors replace Si, we find that, when compared with literature data, the splitting energy for a given shell is almost independent of the identity of the acceptor. For both type-I and type-II spectra, this splitting energy can be successfully explained by the octupole term V 3 alone with k 3 = −2 × 10 5Å4 meV. Comparing the experimental donor and acceptor binding energies with the values calculated by the effective-mass model, this suggests that the shallow donor (N,P) ions can be treated as point charges while the charge distribution of the acceptor ions (Al,Ga,B) is distorted in accord with the T d point group symmetry, resulting in a considerable value for k 3 . This gives a reasonable explanation for the observed splitting energies for both type-I and type-II DAP spectra

Optical properties of GaN grown on porous silicon substrate

International audienceA photoluminescence (PL) study of GaN grown on Si(100) substrate using porous silicon (PS) as an intermediate layer is reported. The samples were characterized using PL for the temperature range 5-300 K under various excitation powers from 5 to 50 mW. For growth temperatures below 800 °C, the room temperature PL shows a broad peak located around cubic GaN emission. This is in clear contradiction with previous scanning electron microscopy and X-ray measurements. At low PL temperature, the observed lines located at 3.306 and 3.364 eV have a narrow full width at half maximum of about 6 and 10 meV, respectively. When the excitation power was varied, no peak shift was observed. These peaks were assigned as deeply localized excitons related to stacking faults near the PS/GaN interface. Quantum confinement (type I or II) due to the presence of nanometric cubic inclusions is another possible explanation for the low-temperature PL