Electronic structure of indium selenide probed by magnetoabsorption spectroscopy under high pressure

Abstract

We report on an investigation of the peculiar electronic structure of the layered semiconductor InSe by magneto-optical experiments under high pressure up to 5 GPa. Magneto-absorption spectroscopy is performed under pulsed magnetic field up to 53 T using a specific setup. Excitonic magnetofingerprints and high-field oscillatory magnetoabsorption yield significant details on the band structure. In addition, the application of an external pressure unveils phenomena that confirm the specific k • p model proposed for this compound on the basis of earlier measurements.

The direct-to-indirect band gap crossover in two-dimensional van der Waals Indium Selenide crystals

“…The measured diamagnetic shifts δE range from 2 to 4 meV at B  = 30 T (see Fig. 4b) and are smaller than the shift reported for the free exciton in bulk InSe ( δE  = 5.1 meV at B  = 30 T)24. Furthermore, a spin-splitting of the lines cannot be resolved even at B  = 30 T. This indicates that the effective g -factor and corresponding splitting ( gμ B B ) are small compared to those ( g  > 9 and gμ B B  > 15 meV at B  = 30 T) measured for localized excitons in TMDCs25.…”

“…For the sample shown in Fig. 5a,b, the low T (4.2 K) PL band emission, labelled X, is centred at ~1.33 eV, at the energy of the free exciton in bulk InSe24. At B  > 15 T, the intensity of the X-band increases and its shift δE has a linear dependence on B, i.e.…”

Electronic and optical properties of two-dimensional InSe from a DFT-parametrized tight-binding model

“…A calculation with the LDA returns the band gap for bulk InSe as 0.41 eV as compared to the bulk experimental value of 1.40 eV at low temperature 32,50 (1.25 eV at room temperature 17 ). Hence, we subtract δE 0K g ≈ 0.99 eV from the energies of all valence band states while keeping the conduction band energies unchanged for bulk, few-layer, and monolayer InSe.…”

“…While in its bulk form InSe [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36] is a direct gap semiconductor 37 , its electronic structure undergoes significant changes upon exfoliation to few-layer or monolayer thickness, with particularly interesting optical properties observed in recent experiments 1,38 . Density functional theory (DFT) calculations for single layer crystals of InSe 39,40 predict a large increase in the band gap as compared to bulk crystals, with the valence band maximum slightly shifted from the Γ point.…”

Red-green luminescence in indium gallium nitride alloys investigated by high pressure optical spectroscopy

“…[3][4][5] The power of these methods stems from the different sensitivity to an external stress between band states and localized electronic states. In addition, pressure dependent optical experiments provide essential benchmarks to improve our ability to accurately predict the electronic properties of these highly promising materials.…”