Papers by Keyword: Bound Exciton

Abstract: Though the crystal growth technology of SiC is improving steadily, it is still crucial to reduce crystalline defects which act as carrier recombination (CR) centers and deteriorate device performance. We detected CR centers in a p-type 4H-SiC substrate by observing the intensity change of photoluminescence due to the addition of a below-gap excitation (BGE) light of 0.93[eV]. We noticed the temperature and the BGE density dependence of band edge (BE) emission in addition to donor acceptor pair (DAP) emission and discriminated the temperature effect from that of BGE. The BGE density dependence of the PL intensity quenching is different among the BE emission, B₀- and C₀-lines of the DAP, respectively. It gives us an important clue for understanding CR mechanisms inside the bandgap of SiC.

Abstract: Photoluminescence from excitons bound to shallow donors or acceptors was studied in Al-, As-, B-, Ga- and P-doped Ge. Excitons bound to Al and B acceptors were identified for the first time. The dissociation energy of the excitons satisfies Haynes rule and changes with a factor of 0.1 linearly with the ionization energy of the dopants.

Abstract: Photoluminescence (PL) spectra of 3C-SiC(n,p)/6H-SiC(n) and 3C-SiC(p)/15R-SiC(n) heterostructures have been studied. A broad structureless band, absent in PL spectra of n–n heterostructures, was observed in the spectrum of p–n heterostructures in the energy range 2.2–2.4 eV. It is suggested that this band is due to the presence of a 2D electron gas in a quantum well near the heterointerface. High (~ 4000 cm2/s V) value of electron mobility and the absence of any significant fall in the mobility temperature dependence at liquid-nitrogen temperatures confirm the existence of a 2DEG in the QW at the heterointerface.

Abstract: We report isotope shifts of the no-phonon lines of V_Si+H/D complexes observed in lowtemperature photoluminescence spectra of proton/deuteron implanted and annealed samplesshowing both the hydrogen and deuterium spectra. We propose that the isotope shift of the nophonon lines is related to the zero-point energies of the vibrations in both the electronic ground andexcited states of the complex. The red shift of the deuterium no phonon line with respect to thehydrogen line is consistent with a stiffer spring constant for the potential well associated with theexcited state. We tentatively assign a weak shoulder on the H^s₃ first harmonic line to the ¹³C isotope.