Conducting (Si-Doped) Aluminum Nitride Epitaxial Films Grown by Molecular Beam Epitaxy
- PDF / 713,411 Bytes
- 6 Pages / 417.6 x 639 pts Page_size
- 95 Downloads / 234 Views
ABSTRACT As a member of the III-V nitride semiconductor family, AIN, which has a direct energygap of 6.2eV, has received much attention as a promising material for many applications. However, despite the promising attributes of AIN for various semiconductor devices, research on AIN has been limited and n-type conducting AIN has not been reported. The objective of this research was to understand the factors impacting the conductivity of AIN and to control the conductivity of this material through intentional doping. Prior to the intentional doping study, growth of undoped AIN epilayers was investigated. Through careful selection of substrate preparation methods and growth parameters, relatively low-temperature molecular beam epitaxial growth of AIN films was established which resulted in insulating material. Intentional Si doping during epilayer growth was found to result in conducting films under specific growth conditions. Above a growth temperature of 900'C, AIN films were insulating, however, below a growth temperature of 900'C, the AIN films were conducting. The magnitude of the conductivity and the growth temperature range over which conducting AIN films could be grown were strongly influenced by the presence of a Ga flux during growth. For instance, conducting, Si-doped, AIN films were grown at a growth temperature of 940°C in the presence of a Ga flux while the films were insulating when grown in the absence of a Ga flux at this particular growth temperature. Also, by appropriate selection of the growth parameters, epilayers with n-type conductivity values as large as 0.2 Q-1 cm'1 for AIN and 17 Qf'cm' for Al0 75Gao. 25N were grown in this work for the first time. INTRODUCTION Research on the III-V nitride materials system (AIN, GaN, InN, and their ternaries) has been one of the hottest issues in current materials research. Ever since the successful fabrication of the first highly efficient blue-light-emitting diodes [1] and blue-diode lasers [2], enormous attention has been given to the III-V nitrides. The III-V nitride materials are not only good candidates for optoelectronic devices, but also promising materials for high temperature, high frequency, and high power electronic device applications [3]-[6]. Among the III-V nitrides, AIN has recently drawn attention due to its potential for use in many device application areas. AIN displays high thermal conductivity, high temperature stability and a large direct band-gap of 6.2eV and has attractive piezoelectric properties, which render it suitable for surface acoustic wave device applications [7]. AIN (and high Al content AlGaN) is also of particular interest due to its negative electron affinity [8], which can be exploited for cold cathode applications in high power vacuum electronics and flat panel displays. Despite these promising attributes, however, progress in the development of AIN-based devices has been limited due to difficulties encountered in doping the material. Attempts to dope AIN have been made by several researchers [9]-[l 11, however, all of
Data Loading...
