Electrical properties of indium selenide single crystals (original) (raw)
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Electrical properties of indium selenide single crystals doped with tin
Solar Energy Materials and Solar Cells, 1992
Resistivity, Hall effect and deep level transient spectroscopy measurements have been performed on Sn-doped InSe single crystals grown by the Bridgman-Stockbarger method. The electrical properties of the investigated samples are dominated by a donor level attributed to the dopant at about 50 meV from the conduction band. The temperature dependence of electron Hall mobility is explained by combining the optical phonon, the ionized and the neutral impurity scatterings. According to Schimd's model an electron-phonon coupling constant g2= 0.065 is determined. Finally, an electron trap has been detected at about 0.62 eV below the conduction band with a capture cross section of about 5 x 10 16 cm 2.
Indium selenide: an insight into electronic band structure and surface excitations
Scientific Reports, 2017
We have investigated the electronic response of single crystals of indium selenide by means of angle-resolved photoemission spectroscopy, electron energy loss spectroscopy and density functional theory. The loss spectrum of indium selenide shows the direct free exciton at ~1.3 eV and several other peaks, which do not exhibit dispersion with the momentum. The joint analysis of the experimental band structure and the density of states indicates that spectral features in the loss function are strictly related to single-particle transitions. These excitations cannot be considered as fully coherent plasmons and they are damped even in the optical limit, i.e. for small momenta. The comparison of the calculated symmetry-projected density of states with electron energy loss spectra enables the assignment of the spectral features to transitions between specific electronic states. Furthermore, the effects of ambient gases on the band structure and on the loss function have been probed.
Physical Review B, 1997
In this work we report on Hall effect, resistivity and thermopower measurements in n-type indium selenide at room temperature under either hydrostatic and quasi-hydrostatic pressure. Up to 40 kbar (= 4 GPa), the decrease of carrier concentration as the pressure increases is explained through the existence of a subsidiary minimum in the conduction band. This minimum shifts towards lower energies under pressure, with a pressure coefficient of about-105 meV/GPa, and its related impurity level traps electrons as it reaches the band gap and approaches the Fermi level. The pressure value at which the electron trapping starts is shown to depend on the electron concentration at ambient pressure and the dimensionality of the electron gas. At low pressures the electron mobility increases under pressure for both 3D and 2D electrons, the increase rate being higher for 2D electrons, which is shown to be coherent with previous scattering mechanisms models. The phase transition from the semiconductor layered phase to the metallic sodium cloride phase is observed as a drop in resistivity around 105 kbar, but above 40 kbar a sharp nonreversible increase of the carrier concentration is observed, which is attributed to the formation of donor defects as precursors of the phase transition.
Cumhuriyet Science Journal, 2019
Structural, morphological and optical properties of undoped and boron doped Indium Selenide (InSe) thin films grown on glass and layered Gallium Selenide (GaSe) single crystal substrates with SILAR method have been investigated by XRD, AFM and UV-Vis spectrophotometer techniques. XRD measurements showed that the crystal structure of InSe thin films grown on glass substrates were hexagonal P61 γ-In2Se3 with lattice parameters a=7.1286 Å, c=19.382 Å and z=6 while the InSe thin films grew as hexagonal P63/mmc InSe with lattice parameters a=4.005 Å, c=16.640 Å and z=4 on GaSe single crystal substrates. The AFM images showed that average particle sizes of undoped and boron doped InSe thin films were found to be varying between 26.5-60.2 nm and 30.9-101.5 nm grown on glass and GaSe single crystal substrates, respectively. The optical absorption spectra of undoped and boron doped InSe thin films grown on both glass and GaSe single crystal substrates showed absorption maxima around the 2.00 and 2.24 eV, respectively. The calculated Urbach energies of the InSe thin films grown on glass substrates were found bigger than those of the InSe thin films grown on GaSe single crystal substrates.
Sub-bandgap analysis of boron doped InSe single crystals by constant photocurrent method
Optical Materials, 2014
Sub-bandgap absorption properties of indium selenide doped with boron atoms within a range of [B] = 0-1.8 at.% have been investigated. From the absorption coefficient spectra measured by using constant photocurrent method (CPM) at 300 K, we observed that the disorder in the structure increases. The calculated Urbach parameters, quantifying the disorder, vary from 17 to 53 meV, as [B] is increased from 0 to 1 at.%. Also the calculated optical gaps decrease from 1.28 eV to 1.17 eV for the same range of [B]. From temperature dependent dark conductivity measurements, the characteristic activation energies are calculated to range from 0.25 to 0.18 eV for vertical (to c-axis) direction; to stay almost constant for parallel (c-axis) direction. At a temperature of 12 K, the absorption coefficient spectra by using CPM and the radiative recombination spectra by photoluminescence (PL) have been taken for the samples with [B] = 0 and 0.5 at.%. Three main PL bands are observed at photon energies of 1.24,1.306and1.337eV.ThePLbandsareinterpretedbycorrespondingabsorptionbandsdetectedat12Kandatthephotonenergiesof1.24, 1.306 and 1.337 eV. The PL bands are interpreted by corresponding absorption bands detected at 12 K and at the photon energies of 1.24,1.306and1.337eV.ThePLbandsareinterpretedbycorrespondingabsorptionbandsdetectedat12Kandatthephotonenergiesof1.24, 1.31and1.31 and 1.31and1.35 eV.
Materials Research Express, 2019
The effects of annealing and variation of temperature on the electrical and thermoelectric properties of e-beam evaporated InSe thin films has been investigated in details. The XRD study demonstrates that the as-deposited InSe thin films are amorphous while they become polycrystalline with the presence of In3Se4 phase after annealing. The SEM micrographs reveal that the surfaces of as-deposited films are smooth whereas they become non-uniform due to annealing. The heating and cooling cycles of the as-deposited films exhibit that the resistivity of the films shows an irreversible phase-transition and become stable after 3-4 successive heattreatment operations in air. The electrical conductivity of annealed InSe thin films shows a highly degenerate semiconducting (metallic) behavior. The thermopower of the annealed films indicates that InSe thin film is a highly degenerate n-type semiconductor i.e. metallic. Thickness dependence thermopower obeys the Fuchs-Sondheimer theory. The optical band gap of the annealed films increases as compared to the as-deposited films. These results indicate that InSe thin films encounter a phase-transformation from In2Se3 to a new In3Se4 metallic phase with an optical band gap of ~1.8 eV due to heat-treatment.
Electrical transport properties of impurity-doped In2Se3
physica status solidi (a), 1986
The electrical transport properties of In,Se, and of impurity-doped In,Se, are investigated. An attempt is made to throw light on the origin of the free carrier concentration in annealed and quenched samples. The temperature dependence of the electrical conductivity and Hall mobility of sulfur-and lithium-doped In,Se, are studied. A number of native electrically active centres is proposed whose concentration virtually does not vary upon doping with donor-like or acceptorlike impurities. A detailed study is made on the effects of the deviation from the stoichiometry by impurity doping. Les propriBt6s Blectriques du semiconducteur In,Se, et du matBriau dope ont BtB BtudiBes. Une tentative de comprBhension de I'origine des porteurs libres dans le matbriau recuit et trempk est faite. L'Btude de la conductivitb e t de la mobilite de Hall dans In,Se, dopb au soufre e t au lithium a BtB menhe. Nous proposons un nombre de centres donneurs actifs Blectriquement simples dont la concentration ne varie virtuellement pas quand on dope par des impuretbs de type donneur ou accepteur. Une Btude d6taillBe est faite sur les effets de changements de stoechiombtrie par l'introduction d'impuretks.
The Advent of Indium Selenide: Synthesis, Electronic Properties, Ambient Stability and Applications
Nanomaterials (Basel, Switzerland), 2017
Among the various two-dimensional semiconductors, indium selenide has recently triggered the interest of scientific community, due to its band gap matching the visible region of the electromagnetic spectrum, with subsequent potential applications in optoelectronics and especially in photodetection. In this feature article, we discuss the main issues in the synthesis, the ambient stability and the application capabilities of this novel class of two-dimensional semiconductors, by evidencing open challenges and pitfalls. In particular, we evidence how the growth of single crystals with reduced amount of Se vacancies is crucial in the road map for the exploitation of indium selenide in technology through ambient-stable nanodevices with outstanding values of both mobility of charge carriers and ON/OFF ratio. The surface chemical reactivity of the InSe surface, as well as applications in the fields of broadband photodetection, flexible electronics and solar energy conversion are also disc...
Solar Energy Materials and Solar Cells, 1992
The temperature dependence of the Hall effect has been studied on lnSe single crystals doped with Cl. The electron mobility can be explained by combining the homopolar optical-phonon and the ionized impurity scatterings. Moreover, two electron traps of depths 0.66 and 0.30 eV have been investigated by deep-level transient-capacitance spectroscopy measurements (DLTS). The first level is present in both pure and doped samples, while the second level only appears in doped samples.