xEgGaAs

xEgGaAs is not a widely standardized material designation in semiconductor literature. In some contexts the label is used informally to refer to a GaAs-based alloy with a tunable bandgap Eg, where a composition parameter x indicates how much of a modifying component is present. Alternatively, it may be shorthand for related GaAs1−xGex or Ge-doped GaAs. Because there is no consensus definition, interpretations vary between studies.

Most plausible interpretations describe a zinc blende crystal whose lattice constant and bandgap vary with composition according to Vegard’s law. The undoped GaAs bandgap at room temperature is about 1.42 eV, and alloying or doping can shift Eg upward or downward depending on the additive and its interaction with the GaAs matrix. The exact optical and electronic properties depend on the chosen interpretation of x and the resulting lattice strain.

Fabrication methods commonly cited for GaAs-based alloys include metalorganic chemical vapor deposition (MOCVD) and molecular beam epitaxy (MBE). Growth on GaAs or Ge substrates, with careful control of temperature, V/III ratio, and dopant species, influences composition, strain, and defect density. Ge-containing dopants can act as donors, altering carrier concentration and mobility, though effects on the band structure are material- and composition-dependent.

Potential applications align with GaAs-based optoelectronics and high-speed electronics, including photodetectors, LEDs, laser diodes, and high-frequency devices. The specific device performance is tied to the actual composition, structure, and growth conditions associated with the interpretation of x in xEgGaAs.

See also: GaAs, GaAs1−xGex, AlGaAs, InGaAs, Ge-doped GaAs.