ABSTRACT

IIIb-Vb compounds, which consist of the group IIIb and Vb elements of the periodic table, include important semiconductors such as GaP, GaAs, GaN, and InP. These materials are not used for phosphors in a polycrystalline form as is the case of IIb-VIb compounds, but they are utilized for many optoelectronic devices such as light-emitting diodes, semiconductor lasers, and photodiodes in a single crystalline form of thin films. The materials composed of lighter elements tend to be more ionic than those composed of heavier elements. This trend is reflected in their crystal structure and energy gap; the wurtzite structure and wider gaps are prevalent in lighter materials, while the zinc-blende structure and narrower bandgaps occur in heavier materials. AlP, AlAs, GaP, GaAs, and InP are located between the above two extremes. Their bandgaps range from the near-infrared to the visible light region, and these materials and related alloys of AlGaAs, GaPAs, GaInP, GaInAs, and GaAlPAs are materials for the optoelectronic applications.