T.C. Harman

Collisional narrowing of infrared water‐vapor transitions

Water‐vapor absorption lines in the ν2 band involving transitions between states of high rotational energy have been found to undergo substantial collisional narrowing in the presence of buffer gases. Measurements were carried out near 5.35 μm, using tunable lead sulfide selenide semiconductor diode lasers.

Tunable diode laser measurements of water vapour absorption line parameters

Tunable diode laser measurements of water vapour lines in the 5 μm region have been extended to include oxygen as well as nitrogen broadening. Positive pressure shifts of line positions have been observed for the first time in the v 2 band. Absolute calibration of a line position using the CO laser as a reference has also been carried out.

Single heterojunction Pb1−x Snx Te diode lasers

Single heterojunction diode lasers in the Pb1−xSnx Te alloy system have been fabricated by low‐temperature vacuum deposition of n‐PbTe on a p‐Pb0.88Sn0.12 Te substrate. The lasers have lower threshold current densities and operate cw at higher temperatures than homojunction devices in this material. At laser threshold the incremental diode resistance drops abruptly from 0.5 Ω to a series resistance limited value of 0.08 Ω, a previously unobserved effect in diode lasers which indicates very high internal quantum efficiency.

Tunable laser measurements of water vapor transitions in the vicinity of 5 μm

Abstract The present results confirm earlier tunable laser observations that the atmospheric widths of high rotational energy transitions are considerably narrower than previously predicted. Intensities, self-broadening coefficients, nitrogen and air shifts, and relative positions have also been measured.

Obervation of Λ-doubling and Zeeman splitting in the fundamental infrared absorption band of nitric oxide

Abstract A high resolution infrared study of the R( 15 2 ) vibration-rotation transition in 14N16O has been performed using a narrow linewidth (≈ 1 MHz) tunable PbSSe semiconductor laser. Small splittings due to Λ-type doubling and the Zeeman effect have been fully resolved (resolution ≈a 5 × 107), limited only the Doppler width in the low pressure gas.

p‐n Junction Photodiodes in PbTe Prepared by Sb+ Ion Implantation

n‐p junction photovoltaic detectors in PbTe have been fabricated using Sb+ ion implantation to create the n‐type layer. At 77 °K, 15‐mil square diodes have had zero‐bias resistances as high as 15 MΩ for a resistance‐area product of 2.1×104 Ωcm2. Peak detectivities at 4.4 μm in reduced background as high as 1.6×1012 cmHz1/2/W were observed. Diode quantum efficiencies were typically 40% at 4.4 μm.

Pb1−xSnxTe photovoltaic diodes and diode lasers produced by proton bombardment

Abstract N-p junction photovoltaic detectors in Pb0.88Sn0.12Te and laser diodes in both PbTe and Pb0.88Sn0.12Te fabricated using proton bombardment to create the n-type layer are reported. Zero-bias resistance area products as high as 1.4 Ω-cm2 at 77°K and 966 Ω-cm2 at 15°K were observed for 15-mil-square Pb0.88Sn0.12Te photodiodes. At 77°K, peak detectivities at 7.5 μm as high as 2.5 × 1010 cmHz1 2 /W were measured. At 15°K, the peak detectivity occurred at 10.2 μm and in reduced background was greater than 10 12 cmHz1 2 / W . Both PbTe and Pb0.88Sn0.12Te laser diodes operated CW at 4.2°K. The PbTe diodes exhibited single mode CW laser operation up to at least 50°K and pulsed operation up to at least 80°K.

High‐resolution spectroscopy using magnetic‐field‐tuned semiconductor lasers

Tunable laser spectroscopy measurements on low‐pressure gases have been performed using magnetic‐field‐tuned lead‐salt semiconductor diode lasers in the 4‐ to 7‐μm region. Use of magnetic field tuning in conjunction with the conventional current tuning is shown to significantly increase the versatility of diode lasers in high‐resolution spectroscopy. Details of the tuning characteristics for fields up to 90 kG are presented.

PbS photodiodes fabricated by Sb+ ion implantation

N-p junction photodiodes in PbS have been fabricated using Sb+ ion implantation to create the n-type layer. At 300°K, 15-mil-square diodes have shown typical zero-bias resistances of 200 Ω corresponding to a resistance-area product of 0.28 Ω-cm2. At 195°K, the zero-bias resistance increased to 50 kΩ for a resistance-area product of 70 Ω-cm2, and at 77°K, the zero-bias resistance was 5 × 109 Ω for a resistance-area product of 7 × 106 Ω-cm2. Peak detectivities occurred at 2.55, 2.95, and 3.4 μm at 300°K, 195°K and 77°K, respectively. The corresponding measured detectivities were 4.8 × 109, 1.1 × 1011 and 4.2 × 1012 cm Hz12/W. The 77°K detectivity was measured in a reduced background and was amplifier noise limited. Peak quantum efficiencies were typically 50–60 per cent.

The Nernst-Ettingshausen energy conversion figure of merit for Bi and Bi-4% Sb alloys

Abstract The Nernst-Ettingshausen (NE) energy conversion figure of merit ZNE has been measured by a direct method for Bi and Bi-4% Sb at various temperatures and magnetic fields. The experimental data show that ZNE for pure Bi is greater than ZNE for the Bi-4% solid solution.