18855-94-2Relevant articles and documents
Stacy, A. M.,Hodul, D. T.
, p. 405 - 410 (1985)
Ohno, Y.,Hirama, K.,Nakai, S.,Sugiura, C.,Okada, S.
, (1983)
Piezooptical studies of group 4B transition metal disulfides ZrS 2 and HfS2
Terashima, Koichi,Imai, Isamu
, p. 1814 - 1823 (1991)
Piezotransmission spectra near the indirect absorption edge and piezoreflectance spectra in the visible region of group 4B transition metal disulfides ZrS2 and HfS2 have been studied by the stress modulation technique at 77 K. The uniaxial stress X was applied along the a axis and the spectra were measured using the polarized light, E//X and E⊥X, where E is the electric field of the incident light. The change of the energy levels by the strain is evaluated by comparing the piezo-modulated spectra with the wavelength-modulated spectra. The main peak and the broad structure at higher energy side in the spectra originate from the overlapping of the transitions at and near T point and the other structures at lower energy side are due to the transitions at L and M points.
Material Design of Green-Light-Emitting Semiconductors: Perovskite-Type Sulfide SrHfS3
Hanzawa, Kota,Iimura, Soshi,Hiramatsu, Hidenori,Hosono, Hideo
, p. 5343 - 5349 (2019/03/29)
A current issue facing light-emitting devices is a missing suitable material for green emission. To overcome this, we explore semiconductors possessing (i) a deep conduction band minimum (CBM) and a shallow valence band maximum (VBM), (ii) good controllability of electronic conductivity and carrier polarity, and (iii) a directly allowed band gap corresponding to green emission. We focus on early transition metal (eTM)-based perovskites. The eTM cation's high and stable valence state makes its carrier controllability easy, and the eTM's nonbonding d orbital and the anion's p orbital, which constitute the deep CBM and shallow VBM, are favorable to n- and p-type doping, respectively. To obtain a direct band gap, we applied a scheme that folds the bands constituting the VBM at the zone boundary to the zone center where the CBM appears. Orthorhombic SrHfS3 was chosen as the candidate. The electrical conductivity was tuned from 6 × 10-7 to 7 × 10-1 S·cm-1 with lanthanum (La) doping and to 2 × 10-4 S·cm-1 with phosphorus (P) doping. Simultaneously, the major carrier polarity was controlled to n type by La doping and to p type by P doping. Both the undoped and doped SrHfS3 exhibited intense green photoluminescence (PL) at 2.37 eV. From the PL blue shift and short lifetime, we attributed the emission to a band-to-band transition and/or exciton. These results demonstrate that SrHfS3 is a promising green-light-emitting semiconductor.
