Effect of Magnetic Field on the Threshold Current in InAs and InSb Laser Diodes

Effect of Band Tails on Stimulated Emission of Light in Semiconductors

Abstract: The dependence of the stimulated emission of radiation in semiconductors on temperature and on impurity concentration has been calculated using a Kane model with a Gaussian band tail for the density of states, and an optical model with a constant matrix element and no selection rule for the radiative transitions The screening length and the characteristic energies for the widths of the conduction- and valence-band tails are calculated by a self-consistent procedure, and the calculation has no adjustable parameters Numerical results are obtained using parameters appropriate for GaAs injection lasers The presence of band tails leads to a more nearly linear dependence of gain on excitation level, in better agreement with experiment, than did the calculation without band tails by Lasher and Stern Increasing impurity concentration leads to a weaker temperature dependence of the excitation rate required to reach a given gain

Electron Interaction Effects on Recombination Spectra

Abstract: This note suggests a possible origin of low energy tails observed in radiative recombination when at least one of the participating bands is degenerate. An order-of-magnitude calculation is made which shows that the effect can have the same origin as similar effects in the soft X-ray emission spectra of metals. Furthermore, it is suggested that the analysis of experimental tails can lead to information about the screening lengths in the Coulomb interaction between electrons in bands. Dieser Beitrag weist auf eine mogliche Ursache fur die Auslaufer niedriger Energie hin, die bei der strahlenden Rekombination beobachtet werden, wenn eines der beteiligten Bander entartet ist. Eine grosenordnungsmasige Abschatzung wird durchgefuhrt, die zeigt, das der Effekt die gleiche Ursache haben kann wie ahnliche Effekte bei Emissionspektren weicher Rontgenstrahlung der Metalle. Weiterhin wird darauf hingewiesen, das eine Analyse der experimentell gefundenen Auslaufer zu einer Information uber die Abschirmlangen der Coulombwechselwirkung zwischen den Elektronen in den Bandern fuhren kann.

Recombination Emission in InSb

Abstract: Optically excited recombination emission has been studied for $n$- and $p$-type single-crystal samples of InSb at 77 and 4.2\ifmmode^\circ\else\textdegree\fi{}K. Emissions associated with band-to-band transitions, transitions with creation of an optical phonon, and transitions involving acceptor impurities have been observed. The band-to-band emission in the pure samples can be attributed to direct transitions, whereas the emission in samples of high donor concentrations clearly shows transitions violating wave-vector conservation. The emission of phonon-assisted transitions is about 150 times weaker than that of direct transitions; this ratio is consistent with the strength of polar-mode coupling. The $n$-type as well as the $p$-type samples show an emission band due to electron transitions from the conduction band to some impurity level at 7.5 meV above the valence band, and the emission is much more prominent in the Zn-doped samples. Germanium-doped $p$-type samples show a weak emission band associated with an acceptor level at 17 meV above the valence band. Samples of large donor concentrations show the effect of band tailing. The main impurity emission increases linearly while the band-to-band emission increased quadratically with the intensity of exciting light. From the shift and splitting of the emission under applied magnetic field, an electron effective mass of ${m}_{e}\ensuremath{\sim}0.018m$ and an electron $g$ factor of $|g|=40 \mathrm{at} 30$ kG are obtained. Electroluminescence has been observed in $p$-type crystals under pulsed electric fields of \ensuremath{\sim}60 V/cm. The observed spectrum appears to be a broadened impurity line. The emission is more than an order of magnitude weaker than optically excited emission corresponding to the same sample conductance.

Threshold relations and diffraction loss for injection lasers

Abstract: Mathematical expressions are derived for the minimum current density necessary to cause stimulated emission in injection lasers. A new type of diffraction loss for a thin light-emitting layer surrounded by light-absorbing material is calculated.