Molecular beam epitaxy

Electron trapping centers in n‐GaAs grown by molecular beam epitaxy (MBE) have been studied by deep‐level transient capacitance spectroscopy (DLTS). At least nine different electron traps are observed with energies ranging from 0.08 to 0.85 eV from the conduction band. Total electron trap concentrations in various samples range from the low 1014 cm−3 range to the mid 1012 cm−3 range. Studies of samples from various growth systems indicate that these traps are most likely due to chemical impurities. A comparison is made with electron traps in n‐GaAs grown by vapor‐ and liquid‐phase epitaxy as well as with the electron traps introduced into n‐GaAs by 1‐MeV electron irradiation.

Study of electron traps in n‐GaAs grown by molecular beam epitaxy

Metal‐semiconductor surface barriers were formed by epitaxially grown Al(001) on GaAs(001) with MBE at room temperature. The diodes exhibit nearly ideal electrical characteristics. It is also demonstrated that different barrier heights may be achieved by growing Al layers on MBE GaAs surfaces with different surface stoichiometries.

Single‐crystal‐aluminum Schottky‐barrier diodes prepared by molecular‐beam epitaxy (MBE) on GaAs

Molecular beam epitaxy (MBE) n−type GaAs layers are commonly doped with Sn, Si, and Ge. The abrupt doping profiles resulting from these three dopants differed significantly when the epitaxy was carried out between temperatures ranging from 550 to 615 °C. The abrupt doped profile of Sn−doped GaAs layers when grown above 550 °C did not follow the time−intensity profile of the dopant beam, while layers doped with Si or Ge did. In the case of Sn, the effect is attributed to surface segregation during deposition.

Impurity profiles of GaAs epitaxial layers doped with Sn, Si, and Ge grown with molecular beam epitaxy

A study of ZnTe films grown on glass substrates using an atomic layer evaporation method

Studies of the doping profile characteristics of molecular‐beam epitaxy (MBE) of GaAs on GaAs substrates are reported. Highly resistive regions at the substrate—epitaxial‐layer interface, and within the epitaxial layer, may occur if the growth is interrupted. It is shown that almost any arbitrary voltage dependence of the capacitance of such structures can be achieved by varying the dopant deposition rate during epitaxy. To illustrate the versatility of this growth technique, voltage‐variable capacitors have been prepared with Schottky barriers on MBE GaAs layers with precisely controlled doping profiles. Low‐frequency measurements (up to 100 MHz) demonstrate that capacitance variations in excess of a factor of 10 have been achieved by varying the applied bias voltage V from 0.3 V (with no significant forward conduction) to −1.0 V. The feasibility of frequency tuning diodes with C−1/2[sine wave]φ−V, where φ is the effective barrier height, is shown. At ‐3 V bias, cutoff frequencies >40 GHz have been measu...

A. Y. Cho

Papers

Interface and doping profile characteristics with molecular‐beam epitaxy of GaAs: GaAs voltage varactor