J. I. Pankove

Photoluminescence of ion‐implanted GaN

Thirty‐five elements were implanted in GaN. Their photoluminescence spectra were measured and compared to those of an unimplanted control sample. Most impurities emit a peak at about 2.15 eV. Mg, Zn, Cd, Ca, As, Hg, and Ag have more characteristic emissions. Zn provides the most efficient recombination center. A set of midgap states is generated during the damage‐annealing treatment.

Neutralization of acceptors in silicon by atomic hydrogen

Atomic hydrogen can neutralize the following acceptors in silicon: boron, aluminum, gallium, and indium. Up to 1019 B cm−3 have been neutralized. Hydrogen penetration seems to follow a diffusive transport that is impeded by the concentration of binding sites.

Hydrogenation and dehydrogenation of amorphous and crystalline silicon

The dehydrogenation of amorphous silicon leaves dangling bonds which can be rehydrogenated by exposure to atomic H, but not to undissociated H2. The hydrogenation of dangling bonds in crystalline Si was monitored via the I (V) characteristics of a p‐n junction.

Light‐induced radiative recombination centers in hydrogenated amorphous silicon

Laser irradiation of hydrogenated amorphous silicon produces recombination centers which shorten the lifetime of carriers. Some of the light‐induced centers are radiative. The generation of the new radiative recombination centers increases with increasing temperature. All the light‐induced centers disappear upon thermal anneal at about 210 °C.

Luminescence in GaN

Abstract This paper contains a brief survey of the major studies done thus far on GaN. This wide gap material offers the possibility of generating light over a large range of wavelength, including the visible and the near ultraviolet. Various aspects of material synthesis, optical properties, and electroluminescent device performance will be reviewed.

Photoemission from GaN

Photoemissive yield measurements were performed on degenerate n‐type and semi‐insulating GaN for heat‐cleaned and for cesiated surfaces. The photoemissive threshold for heat‐cleaned n‐type material occurs at 4.1 eV, while that for semi‐insulating material is beyond 5.5 eV, the experimental spectral range. From these measurements an upper and a lower limit of the electron affinity of heat‐cleaned GaN is derived, namely 4.1 > χ > 2.1 eV. The threshold for cesiated surfaces on both materials is lowered to 1.5 eV, and the photoyield curve exhibits a second threshold at about 3.4 eV. The occurrence of negative electron affinity is suggested for cesiated semi‐insulating GaN.

Violet luminescence of Mg‐doped GaN

The photoluminescent and electroluminescent properties of GaN–GaN:Mg diodes are described. Visible violet electroluminescence was observed with excitation voltages of 10–20 V with the emission peak in the region of 2.9 eV. The I‐V characteristics showed I ∞ V3 in the region where light was emitted, and the observed power efficiency was approximately 10−5. A photoluminescence peak at 2.9 eV provided additional evidence for an acceptor level, associated with the Mg impurity, about 0.5 eV above the valence band.

Electroluminescence in GaN

Abstract Electroluminescence in Zn-doped GaN peaks at 2.6 eV. It is attributed to the injection of holes generated by breakdown at internal boundaries.

Electroluminescence in amorphous silicon

Electroluminescence has been obtained in forward‐biased p‐i‐n diodes, and also in Schottky barrier diodes fabricated from discharge‐produced amorphous Si. The emission at 78 °K in both electroluminescence and photoluminescence peaks at 1.28±0.08 eV in a 0.2‐eV broad band with an external quantum efficiency of ∼10−3.

Amorphous silicon as a passivant for crystalline silicon

Hydrogenated amorphous silicon deposited on a p‐n junction in crystalline silicon causes a two‐order‐of‐magnitude reduction in leakage current compared to the performance of a state‐of‐the‐art thermal oxide passivant.