L. S. Sidhu

Infrared vibration spectra of hydrogenated, deuterated, and tritiated amorphous silicon

This article presents infrared absorption data of amorphous silicon alloys in which the hydrogen isotopes deuterium and tritium have been substituted for hydrogen. Silicon–deuterium and silicon–tritium vibration frequencies are related to silicon–hydrogen vibration frequencies by simple mass relationships. The silicon–deuterium wagging vibration is broadened and blueshifted due to strong coupling to the amorphous silicon network vibrations.

Effect of dangling-bond density on luminescence in tritiated amorphous silicon

Self-luminescence in tritiated amorphous silicon is observed. The substitution of tritium for hydrogen in a hydrogenated semiconductor provides a powerful tool for the study of dangling bonds. The radioactive decay of tritium leads to an increase in the dangling-bond concentration in the material of several orders of magnitude over a period of a few weeks with little other modification in the structure of the material. We report here results of a study of photoluminescence as a function of time in tritiated amorphous silicon. An analysis of the data in terms of a simple theoretical model in which dangling bonds are treated as nonradiative recombination centers yields a capture radius of 32 A for the D0 defect.

Luminescence in hydrogenated amorphous carbon films grown by dc saddle‐field glow‐discharge decomposition of methane

Photoluminescence in hydrogenated amorphous carbon thin films deposited using the dc saddle‐field glow‐discharge technique onto glass and single‐crystal silicon substrates was studied. Samples prepared using positive substrate bias exhibited strong broad‐band photoluminescence at room temperature. The luminescence spectrum had a major peak at 1.9 eV and two smaller peaks at 2.3 and 2.6 eV. Samples prepared using grounded or negatively biased substrates exhibited only weak photoluminescence near 2.6 eV. Infrared spectroscopy indicates that the luminescence at 1.9 and 2.3 eV is related to the presence of C–OH bonds, whereas the photoluminescence at 2.6 eV appears to be an intrinsic property of the a‐C:H films.

Hydrogen incorporation into Si‐doped InP deposited by gas‐source molecular beam epitaxy

Hydrogen incorporation into Si‐doped InP grown by gas‐source molecular beam epitaxy was studied. P‐H sites were identified by infrared spectroscopy. Proton‐implanted reference samples were used to quantify the infrared results. Approximately 0.1 at. % hydrogen was found to be incorporated into InP:Si. Hall measurements indicated that most of the Si atoms were electrically active as donors. Rapid thermal annealing at 600 °C removed most of the bonded hydrogen from the samples. However, this resulted in relatively little change in either the room‐temperature free‐carrier concentration or Hall mobility.

An Infrared and Luminescence Study of Tritiated Amorphous Silicon

Tritium has been incorporated into amorphous silicon. Infrared spectroscopy shows new infrared vibration modes due to silicon-tritium (Si-T) bonds in the amorphous silicon network. Si-T vibration frequencies are related to Si-H vibration frequencies by simple mass relationships. Inelastic collisions of {beta} particles, produced as a result of tritium decay, with the amorphous silicon network results in the generation of electron-hole pairs. Radiative recombination of these carriers is observed. Dangling bonds associated with the tritium decay reduce luminescence efficiency.

Ion bombardment and disorder in amorphous silicon

The effect of ion bombardment during growth on the structural and optical properties of amorphous silicon are presented. Two series of films were deposited under electrically grounded and positively biased substrate conditions. The biased samples displayed lower growth rates and increased hydrogen content relative to grounded counterparts. The film structure was examined using Raman spectroscopy. The transverse optic like phonon band position was used as a parameter to characterize network order. Biased samples displayed an increased order of the amorphous network relative to grounded samples. Furthermore, biased samples exhibited a larger optical gap. These results are correlated and attributed to reduced ion bombardment effects.

Tritium in amorphous silicon

Preliminary results on infrared and luminescence measurements of tritium incorporated amorphous silicon are reported. Tritium is an unstable isotope that readily substitutes hydrogen in the amorphous silicon network. Due to its greater mass, bonded tritium is found to introduce new stretching modes in the infrared spectrum. Inelastic collisions between the beta particles, produced as a result of tritium decay, and the amorphous silicon network, results in the generation of excess electron-hole pairs. Radiative recombination of these carriers is observed.

Saddle-field glow-discharge deposition of amorphous semiconductors

The authors present a dc saddle-field glow-discharge deposition procedure which combines the positive attributes of the conventional dc and rf glow-discharge techniques. Preliminary mass spectra analyses of both silane and methane glow-discharges demonstrates that ions constitute a significant fraction of the species reaching the film surface. Growth rate analyses suggest that ions play a significant role in the saddle-field glow-discharge deposition of amorphous semiconducting films.