Growth of high purity AlN crystals

Optical gain in semiconductors

Light-emitting diodes (LEDs) are devices designed to efficiently convert electrical energy into electromagnetic radiation, most of which is visible to the human eye. Some of the disciplines involved in the understanding and utilization of LEDs are reviewed, with emphasis on the III-V semiconducting compounds and GaP LEDs in particular. Salient features of photometry, the physics of electrical injection and luminescence, and the design of LEDs are discussed in detail, followed by a survey of prominent applications for the various LEDs.

Light-emitting diodes

All defects which are dominated by short-range forces belong to the family of ‘deep’ impurities and exhibit distinctly different properties from the familiar shallow donors and acceptors, where the decisive term is the Coulomb potential. Whereas formation of the shallow states relates to a small part of the Brillouin zone and can be described within the effective mass theory, the opposite is true of the deep states. However, it has recently been shown that the formation of deep localized states in semiconductors can be described with speed and accuracy, and in a self-consistent manner, by exploiting the localized character of the main part of the defect potential. It is possible to project the interaction between the localized potential and the rest of the crystal upon a limited number of localized functions, spanning the range of the potential, with an uncertainty which is small compared to the magnitude of the forbidden gap. This is achieved without truncating proper characterization of the ele...

Deep levels in semiconductors

A study of the luminescence properties of epitaxial GaP containing atomic N grown by molecular beam epitaxy using NH3 and PH3 as the column V sources was conducted. The 77 K photoluminescence spectra of the N‐doped epitaxial GaP showed a continuous redshift, from 5691 A (2.18 eV) to 6600 A (1.88 eV), resulted when the N concentration exceeded ∼5–7×1019 cm−3. This energy shift was found to be consistent with energy gap predictions using the dielectric theory of electronegativity for the GaP1−xNx system. The data also indicate that the emission intensity was maximum for N∼1×1020 cm−3, and then monotonically decreases with increasing N content. This is consistent with the formation of an indirect band‐gap semiconductor.

P.J. Dean

Papers

Recombination processes associated with “Deep states” in gallium phosphide

Electronic structure of ground and excited states of isoelectronic traps

The optical properties of Be, Mg and Zn-diffused gallium phosphide