Engineering topics

Allerman, A. A.

Publications and source records attributed to Allerman, A. A..

2 records

NASA NTRS1997

Quantum cascade light emitting diodes based on type-2 quantum wells

The authors have demonstrated room-temperature CW operation of type-2 quantum cascade (QC) light emitting diodes at 4.2 (micro)m using InAs/InGaSb/InAlSb type-2 quantum wells. The type-2 QC configuration utilizes sequential multiple photon emissions in a staircase of coupled type-2 quantum wells. The device was grown by molecular beam epitaxy on a p-type GaSb substrate and was compared of 20 periods of active regions separated by digitally graded quantum well injection regions. The maximum average output power is about 250 (micro)W at 80 K, and 140 (micro)W at 300 K at a repetition rate of 1 kHz with a duty cycle of 50%.

Light Emitting Diodes↗

NASA NTRS1992

Raman scattering of InGaAs/InP grown by uniform radial flow epitaxy

Uniform radial flow epitaxy, a novel growth technique, has been used to grown InGaAs films on InP. Epitaxial layers above and below the critical thickness for the onset of slip were grown. Raman spectroscopy was used to characterize the quality of epitaxial layers, determine alloy composition, and measure the strain. Raman spectra from both pseudomorphic (strained) and relaxed (unstrained) InGaAs films were obtained at 300 and 80 K. The difference in the frequencies of their GaAs-like longitudinal optical phonons was used to calculate stress for the strained InGaAs/InP, leading to a direct formula for the evaluation of the layer stress.

Feng, Z. C.↗