Carrier density dependence of resonantly pumped magnetically tunable InSb laser

Laser emission in InSb resonantly pumped by a TE CO laser was observed, and the magnetic tuning characteristic was investigated for the samples with different carrier densities. The tuning range of about 8 meV (65 cm?1) was obtained for magnetic fields of up to about 20 kG.     

Carrier density dependence of refractive index in AlGaAs semiconductor lasers

Carrier density dependence of the refractive index in the active layers of semiconductor lasers is evaluated from the wavelength shift with increases in current by taking into account effects of the active layer temperature rise and lateral carrier and optical field distributions on the wavelength shift. The derived refractive index change due to carrier density increase is-4 times 10^{-27}m³, which is in good agreement with the theoretical value.     

Interband Auger recombination in InGaAsP

The interband Auger recombination lifetimes of two Auger processes have been calculated to correlate measured threshold current densities and carrier lifetimes for InGaAsP and InGaAsSb lasers. Good aggreement with experimental data was obtained for lasers with low nominal threshold current densities. These results demonstrate the importance of Auger recombination in the threshold characteristics of InGaAsP/InP lasers.     

Auger recombination in strained quantum wells

A nonthreshold mechanism for Auger recombination of nonequilibrium carriers in quantum wells with strained layers is investigated theoretically. It is shown that the dependence of the Auger recombination rate on the magnitude of the strain and the height of the heterobarriers for electrons and holes can be analyzed only by calculating the overlap integrals between initial and final particle states microscopically. In quantum wells with strained layers the presence of strain affects qualitatively and quantitatively the electron-hole overlap integral. The dependence of the Auger recombination rate on the quantum well parameters, the magnitude of the stress, and temperature are analyzed for heterostructures based on InGaAsP/InP and InGaAlAs/InP. Fiz. Tekh. Poluprovodn. 31, 358–364 (March 1997)     

Auger recombination in long-wavelength strained-layer quantum-wellstructures

A model calculation of Auger recombination in strained-layer InGaAs-InGaAlAs and InGaAs-InGaAsP quantum-well structures is presented as an extension of an empirical Auger theory based on the effective mass approximation. The valence band effective masses around k_∥=0 are calculated by using a six-band Luttinger-Kohn Hamiltonian and the quasi-Fermi levels are determined with a self-consistent Poisson-Schrodinger solver under the effective mass approximation. Three basic Auger processes are considered with the excited carrier being in a bound state of the quantum well, as well as an unbound state. The empirical model includes Fermi statistics as well as a revaluation of the Coulomb interaction overlap integral in the Auger recombination rate. Bound-unbound Auger transitions are proved to be an important nonradiative recombination mechanism in strained-layer quantum-well systems. Our calculations of Auger coefficient are in reasonable agreement with the experimental data     

Auger recombination rate in InGaAsP lasers

For the Auger recombination rate in InGaAsP there is an order of magnitude discrepancy between the measurements by Su et al. and the calculations by Dutta and Nelson, and Sugimura. It is suggested that a major source of this discrepancy is the method used to calculate the overlap integrals. A calculation that supports this suggestion is described.     

A “cold” InP-based tunneling injection laser withgreatly reduced Auger recombination and temperature dependence

We have measured the Auger recombination rates in an InP-based quantum well tunneling injection laser from large signal modulation experiments. Measured values of the Auger coefficient, C_o=1.2±0.6×10^-29 cm⁶ s^-1 at 283 K, are a factor of over 10² smaller than those measured in similar multiple quantum well separate confinement heterostructure lasers. In effect, the tunneling injection mechanism keeps the carriers “cold” even at high injection levels. A maximum value of T_o=70 K is measured in the tunneling injection laser compared to 50 K for conventional quantum well structures,     

Lifetime calculations for Auger recombination in lead-tin-telluride

Calculations of lifetime have been carried out for intervalley Auger processes in PbSnTe. The more generalized treatment, as compared to Emtage's earlier calculations, accounted for 1) nonparabolic dispersion laws, 2) arbitrary statistics, and 3) arbitrary injection level. The lifetime was found to be an order of magnitude larger than the value given by Emtage's formula. As a result, the predicted performance of PbSnTe lasers and infrared detectors may be much better than thought before.     

Temperature dependence of the effective coefficient of Auger recombination in 1.3 μm InAs/GaAs QD lasers

Semiconductor laser heterostructures containing five and ten sheets of InAs/GaAs QDs on GaAs substrates, with an emission wavelength of ～1.3 μm, have been studied. Dependences of the nonradiative lifetime and effective Auger coefficient in QDs are obtained from an analysis of temperature and current dependences of the efficiency of spontaneous radiative recombination. The zero-threshold Auger recombination channel in QDs is shown to dominate at low (below 200 K) temperature, whereas at higher temperatures the quasithreshold channel becomes dominant. The effective 3D Auger coefficient is estimated in the approximation of a spherical QD, and a good agreement with the experimental data is obtained.     

Carrier recombination in gallium arsenide

This paper is concerned with an investigation of the mechanisms responsible for the recombination of excess carriers in gallium arsenide. The photoelectromagnetic and photoconductive techniques are used to measure the carrier lifetimes of n- and p-type samples with carrier concentrations ranging from 10⁷ cm⁻³ to 3 × 10¹⁸ cm⁻³ over temperatures from 80 to 400°K. It is shown that the highest measured minority carrier lifetimes of the more heavily doped samples are controlled by band-to-band radiative recombination. For higher resistivity samples the minority carrier lifetimes are determined by recombination centres lying at the centre of the band gap. Minority carrier trapping at a single level is observed in n-type samples but a more complex trapping model is needed to explain the behaviour of p-type samples.     

Size effects in Auger recombination for InGaAs quantum-wirestructures

A theoretical investigation of Auger recombination in lattice-matched InGaAs/InGaAlAs quantum-wire structures is presented. The valence band structure is calculated by using a four-band Luttinger-Kohn Hamiltonian. CHCC, CHHH, CHHL and CHHS Auger processes are considered with the excited carrier being either in a confined (bound) state of the quantum wire, or an unconfined (unbound) state. The model uses Fermi statistics as well as a revaluation of the Coulomb interaction overlap integral for the calculation of the Auger recombination rate. Bound-unbound Auger processes are proven to be important nonradiative recombination mechanism in quantum-wire systems. It is also found that the Auger coefficient is much more sensitive to the well width in quantum-wire structures than in quantum-well structures     

Suppression of Auger recombination effects in compressivelystrained quantum-well lasers

Based on detailed valence band structure, a Monte Carlo analysis of the Auger recombination effects in compressively strained quantum-well diode lasers has been carried out. The recombination current is found to increase with carrier density, but at a rate far less rapidly than the conventional n³-rule has suggested. At moderate carrier densities, the recombination current is also found to decrease exponentially with increasing strain     

Measurement of Auger recombination in silicon by laser excitation

A new experimental arrangement for the study of Auger recombination in silicon is described and analyzed. A relatively weakly absorbed YAG:Nd laser beam was used for excitation. The decay of the carrier concentration after the injection pulse was studied by measuring the recombination radiation in a direction perpendicular to the laser beam. At some distance from the injection surface the influence of surface recombination and diffusion is then negligible. It has previously been shown that in this geometry the carrier concentration distribution after the laser excitation is accurately described by an analytical expression which accounts for attentuation of the laser beam by both interband and free carrier absorption. Thus the local carrier concentration in the sample can be computed to a high degree of accuracy, which is essential in the determination of the Auger recombination coefficient from decay measurements. Furthermore, this experimental geometry eliminates the problems with laser stray light. Assumptions regarding the influence of surface recombination and diffusion are not necessary in the interpretation of the experiments. The method is usable for silicon in the temperature interval 150–400 K. Preliminary measurements of the Auger coefficient at room temperature are reported.     

Carrier recombination in single crystal PbSe

The photoconductivity decay curves after illumination of single crystal n- and p-type PbSe were analysed assuming recombination through different localized impurity levels in conjunction with direct recombination. The lifetimes deduced for direct (Auger and radiative) recombination below 250 K were in agreement with the calculated values for carrier concentrations 2·10¹⁷ cm⁻³. Furthermore, the existence of up to three impurity levels was concluded from the longer lifetime-components present in the decay curves. Appropriate approximations of the general recombination theory yielded energies separated between 20 and 50 meV from the nearer band edge and minority carrier cross sections 10⁻¹⁷−4·10⁻¹⁹ cm² in the temperature range 250-100 K, and majority carrier cross sections 10⁻¹⁹−10⁻²⁰ cm² at T < 100 K for these levels.     

Carrier recombination at grain boundaries and the effective recombination velocity

The recombination of excess minority carriers at grain boundaries, or other interfaces with space-charge regions, is treated theoretically for general energy distributions of interface states (recombination centers). The distinction is made between minority carrier recombination velocity at the (grain-boundary) interface itself, and the effective recombination velocity for the collection of these carriers by the adjacent space-charge region. Calculations of the effective recombination velocity are made, as a function of the excess minority-carrier concentration at the edge of the space-charge region, since this is the quantity of most convenience for device modelling.     

Carrier loss resulting from Auger recombination in InGaAsP/InP double heterojunction laser diodes: Spectroscopy of 950 nm high energy emission

From 1.3 μm stripe InGaAsP/InP DH lasers, we observed a 950 nm emission band which originates from band-to-band recombination in InP confinement layers. This experimental result can be well explained by considering the overflow of injected carriers from InGaAsP into InP. The overflowed energetic carriers were created by Auger recombination in InGaAsP.     

Evidence of the importance of Auger recombination for InGaAsP lasers

The temperature dependence of Auger recombination in InGaAsP can be described by two regions, one with a slow increase of the Auger coefficient and one with a strong increase. This behaviour is similar to that of the threshold current of an InGaAsP laser. In particular, the slope of the temperature curve of the Auger coefficient changes at T = 255 K, which is exactly the break point temperature of the threshold current. Auger recombination therefore seems to be the most important cause for the temperature dependence of the threshold current in InGaAsP lasers.     

Auger and radiative recombination of acceptor bound excitons in semiconductors

We report on a theoretical and experimental study of acceptor bound exciton recombination. We present calculations of phononless Auger and radiative recombination in direct and indirect band gap materials. We consider hydrogenic acceptors in the direct band gap material Hg_1−xCd_xTe in which the band gap can be varied by changing alloy composition. We present calculations of the Auger transition rate and no-phonon oscillator strengths for the common acceptors in Si and Ge. We have measured the bound exciton lifetimes and no-phonon oscillator strengths for the acceptors in Si and find reasonable agreement with the calculated values.     

Carrier trapping and recombination in avalanche diodes

The differential equations describing an avalanching p⁺nn⁺junction in the presence of multiple-level carrier traps have been solved numerically for trap densities as high as two orders of magnitude greater than the n-region background doping. The results compare quantitatively with a number of past, as well as new, experimentally observed changes in avalanche microwave diode performance with neutron damage. In particular, trapped charge in the space-charge region tends to localize the avalanche region near the p⁺n junction, which raises the frequencies of operation. Carrier trapping at the edges of the space-charge region explains the increase in operating voltage and decrease in small-signal capacitance. The localization of the avalanche region, through carrier trapping in the space-charge region, and recombination effects at high avalanche current densities combine to cause eventual RF failure of IMPATT and TRAPATT diodes with neutron damage.     

Carrier recombination and deep levels in PbTe

The results of transient photoconductivity lifetime measurements and of impurity photoconductivity as well as Hall effect measurements obtained on PbTe films show that deep electron trapping levels exist in monocrystalline epitaxially grown PbTe. To our knowledge this is the first direct observation of deep levels in the gap of PbTe. The energetic position of the levels and their concentration were determined. The observed levels profoundly influenced the efficiency of PbTe infrared emitter diodes. This was shown experimentally by comparing the luminescence intensity of various diodes with different carrier concentration in the active zone. A strong decrease of luminescence intensity was observed for carrier concentrations greater than 10¹⁷ cm⁻³. This decrease could be explained by recombination via the observed levels in the gap.