Electrical properties of polycrystalline GaInAs thin films

• Published in: Thin solid films 2010-10, Vol.519 (1), p.136-144
• Main Authors: Kajikawa, Y., Okuzako, T., Takami, S., Takushima, M.
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Deposition; Electrical properties; Electron mobility; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electronic transport phenomena in thin films and low-dimensional structures; Exact sciences and technology; Fluctuation; Gallium; Grain boundaries; Grain-boundary scattering; Hall-effect measurements; III–V compound semiconductor alloys; Indium gallium arsenide; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Molecular beam epitaxy; Molecular, atomic, ion, and chemical beam epitaxy; Physics; Polycrystalline semiconductor; Potential barriers; Surface and interface electron states; Thermal instruments, apparatus and techniques; Thermionics; Thermometry; Thin films
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2010.07.077

Polycrystalline Ga x In 1 − x As films with x ranging from 0 to 1 were deposited on glass substrates by molecular-beam deposition at 240 or 350 °C. Room temperature Hall-effect measurements showed that the Ga x In 1 − x As films deposited at either temperature exhibit high electron concentrations in the range of 10 18 cm − 3 for x ≤ 0.21 while the electron concentration decreases with increasing Ga content for x ≥ 0.29 to be < 10 15 cm − 3 at x = 0.64. Even at the low deposition temperature of 240 °C, the electron mobility remains > 400 cm 2/(V s) at x ~ 0.2 and then decreases with Ga content to be ~ 40 cm 2/(V s) at x = 0.64. Temperature-varying Hall-effect measurements in the range of 100–390 K revealed that both the electron concentration and mobility of the samples with x ≤ 0.21 are almost independent of the measurement temperature, while those of the samples with x ≥ 0.30 decrease with decreasing measurement temperature. The concentrations and ionization energies of donor levels were deduced from the temperature dependence of the electron concentration with the non-parabolicity of the conduction band taken into account. The temperature dependences of electron mobility in the samples with x ≥ 0.30 are well explained in terms of thermionic electron emission across the grain-boundary barriers assuming fluctuation in potential barrier height, while the almost temperature-independent high electron mobilities in the samples with x ≤ 0.21 are attributed to the absence of potential barrier at the grain boundaries.