An elementary empirical model for the distribution of electronic states an amorphous semiconductor is presented. Using this model, we determine functional form optical absorption spectrum, focusing our analysis on joint density function, which dominates spectrum over range photon energies consider. Applying results, then how measures commonly used to characterize edge semiconductor, such as Tauc gap and tail breadth, are related parameters that underlying states. We, thus, provide...

The temperature dependence of the optical-absorption edge (Urbach edge) GaAs is measured in semi-insulating and n-type (n=2×1018 cm−3) over range from room to 700 °C. Both optical absorption are using a diffuse reflectance technique. characteristic energy exponential found increase linearly with temperature, 7.5 meV at 12.4 °C, for GaAs. dependent part width Urbach six times smaller than predicted by standard theory where proportional phonon population.

The photoluminescence from a Ga(AsBi) sample is investigated as function of pump power and lattice temperature. disorder-related features are analyzed using Monte Carlo simulation technique. A two-scale approach introduced to separately account for cluster localization alloy disorder effects. corresponding characteristic energy scales 11 45 meV deduced the detailed comparison between experiment simulation.

The temperature dependences of the optical absorption edges semi-insulating GaAs and InP have been measured from room to 905 °C 748 °C, respectively, with accuracies ±1 at ±5 900 °C. dependence edge is adequately reproduced by an Einstein model although Varshni gives improved fit band gap. Finally, widths are correlated ionicity.

An air-bridged, 120-nm-thick semiconductor slab with a two-dimensional (2D) square array of through holes on 480 nm pitch (Λ) was fabricated using selective wet etching techniques. The second order photonic resonances the structure were studied by comparing broadband optical scattering data numerical solutions Maxwell’s equations. Features observed in these spectra over 1200 cm−1 range, near 9500 cm−1, indicate that 2D texture splits energy degeneracy modes propagation constants {±2π/Λ,0}...

The structural and optical properties of lattice-matched InAs0.911Sb0.089 bulk layers strain-balanced InAs/InAs1−xSbx (x ∼ 0.1–0.4) superlattices grown on (100)-oriented GaSb substrates by molecular beam epitaxy are examined using X-ray diffraction, spectroscopic ellipsometry, temperature dependent photoluminescence spectroscopy. ellipsometry measurements determine the ground state bandgap energy diffraction layer thickness mole fraction structures studied. Detailed modeling data is employed...

The real and imaginary photonic band structure of modes attached to two-dimensionally textured semiconductor membranes is determined experimentally theoretically. These porous waveguides exhibit large (1000 ${\mathrm{cm}}^{\ensuremath{-}1}$ at 9500 ${\mathrm{cm}}^{\ensuremath{-}1})$ second-order optical gaps, highly dispersive lifetimes, bands with well-defined polarization along directions high symmetry.

GaInAsSbBi alloys are grown lattice-matched on GaSb by molecular beam epitaxy demonstrating smooth surface morphologies, >5 μm wavelength photoluminescence emission, and minority carrier lifetimes >1 μs. At a growth temperature of 400 °C, the Ga flux is systematically increased Bi decreased to identify conditions that yield droplet-free morphologies. The lifetime evaluated using time-resolved photoluminescence, where it observed samples exhibit comparable their Bi-free GaInAsSb...

The temperature of semiconductor substrates used in molecular beam epitaxy is determined from the diffuse reflection spectrum (DRS) substrates, measured with an external light source. relative sensitivity technique better than 1 °C. absolute calibration DRS for different thickness, conductivity and back surface texture, described. also sensitive to changes front roughness as demonstrated by increase reflectance at short wavelengths when oxide desorbs.

The variable stripe length method described by Shaklee and Leheny, [Appl. Phys. Lett. 18, 475 (1971)] is a straightforward way to determine the steady-state gain spectrum of laser material. Here, common sources error are identified several new, robust ways calculating from data presented. advantages these methods underlined applying them obtained Ga(AsSb)∕GaAs∕(AlGa)As heterostructure.

A semi-analytical model is constructed for single- and multi-junction solar cells. This incorporates the key performance aspects of practical devices, including nonradiative recombination, photon recycling within a given junction, spontaneous emission coupling between junctions, non-step-like absorptance emittance with below-bandgap tail absorption. Four typical planar structures combinations smooth/textured top surface an absorbing/reflecting substrate (or backside surface) are...

The characteristic emission from tail states below the bandgap of GaAsBi/GaAs quantum wells is studied using photoluminescence spectroscopy over a 10–300 K temperature range and 0.1–1000 mW pump power range. exhibit two energies: A deeper one that independent at 29 meV nearer to dependent, broadening 17 10 K–29 room temperature. are thought originate localization Bi disorder effects due alloy fluctuations clustering on group-V sublattice.

The optical properties of bulk InAs0.936Bi0.064 grown by molecular beam epitaxy on a (100)-oriented GaSb substrate are measured using spectroscopic ellipsometry. index refraction and absorption coefficient over photon energies ranging from 44 meV to 4.4 eV used identify the room temperature bandgap energy as 60.6 meV. InAsBi is expressed function Bi mole fraction band anticrossing model characteristic coupling strength 1.529 between impurity state InAs valence band. These results programmed...

Strain-balanced InAs/InAsSb superlattices offer access to the mid- long-wavelength infrared region with what is essentially a ternary material system at GaSb lattice constant. The absorption coefficients of grown by molecular beam epitaxy on (100)-oriented substrates are measured room temperature over 30 800 meV photon energy range using spectroscopic ellipsometry, and miniband structure each superlattice calculated Kronig-Penney model. conduction band offset used as fitting parameter align...

Measurements of the transition energies GaAsSb quantum well samples with different barrier configurations reveal that conduction band offset coherently strained ${\mathrm{GaAs}}_{1\ensuremath{-}y}{\mathrm{Sb}}_{y}∕\mathrm{GaAs}$ heterojunction grown on GaAs has a zero crossing at Sb mole fraction $y=0.43\ifmmode\pm\else\textpm\fi{}0.07$. A type-I alignment is formed for lower fractions and type-II higher fractions. This occurs as consequence considerable amount (58%)...

Localization effects on the optical properties of GaAs1−xBix/GaAs single quantum wells (SQWs), with Bi contents ranging from x = 1.1% to 6.0%, are investigated using continuous-wave and time-resolved photoluminescence. The temperature- excitation density dependence PL spectra systematically studied, carrier recombination mechanisms analyzed. At low temperatures, time-integrated emission is dominated by localized electron-hole pairs due varying content clustering in alloy. extracted energy...

We discuss the growth by molecular-beam epitaxy, and studies of low-temperature electrical properties, undoped InAs/AlSb quantum wells. The two-dimensional electron gas realized in wells exhibits high mobility at low temperatures, an analysis its Shubnikov–de Haas oscillations suggests this is limited scattering from remotely located unintentional dopants. Spin splitting clearly resolved 4.2 K, revealing a g-factor as large −60 magnetic fields. size enhancement increases with decreasing...

Room-temperature continuous-wave operation of antimonide-based long wavelength VCSELs is demonstrated, with 1.2 mW power output at 1266 nm, the highest figure reported so far using this material system. Singlemode powers 0.3 10°C and 0.1 70°C sidemode suppression ratios up to 42 dB are also achieved.

The temporal evolution of the spectrally resolved luminescence is measured for a Ga(AsBi) sample at low temperatures. results are analyzed with help kinetic Monte Carlo simulations incorporating two disorder scales attributed to alloy and Bi- clustering. An average time 5 ps identified as upper limit carrier capture into Bi clusters whereas extracted hopping rate associated fluctuations much faster than transitions between individual cluster sites.

Alloying bismuth with InAs provides a ternary material system near the 6.1 Å lattice constant, which covers technologically important mid- and long-wavelength infrared region. One challenge for this is that it not straightforward to incorporate into bulk lattice, since has tendency surface-segregate form droplets during growth. In work, conditions InAsBi growth using molecular beam epitaxy are explored. A window identified (temperatures ⪞ 270 °C, V/III flux ratios 0.98 ⪝ As/In 1.02, Bi/In ≅...

Several 1 μm thick, nearly lattice-matched InAsBi layers grown on GaSb are examined using Rutherford backscattering spectrometry and X-ray diffraction. Random measurements indicate that the average Bi mole fraction ranges from 0.0503 to 0.0645 for sample set, ion-channeling atoms substitutional. The diffraction show a sideband near main (004) peak, indicating is not laterally uniform in layer. out-of-plane tetragonal distortion determined by modeling peaks, which unstrained lattice constant...

The physical characteristics of the fundamental absorption edge semi-insulating GaAs and unintentionally doped GaSb, InAs, InSb are examined using spectroscopic ellipsometry. A five parameter model is developed to describe key edge. Among these parameters bandgap energy, characteristic energy Urbach tail, coefficient at energy. results indicate that Coulomb interaction strongly influences shape band with progressively less influence as decreases. dependence optical transition strength...

Abstract The injection and temperature dependence of the spontaneous emission quantum efficiency molecular beam epitaxy grown GaAs/AlGaAs heterostructures is determined using excitation dependent photoluminescence (PL) measurements. Two samples are compared; one with Sb as a surfactant without Sb. PL measurements were performed at temperatures from 80 to 320 K HeNe pump laser powers ranging 0.6 35 mW. inferred power law predicted by rate equations that links integrated signal. use improved...