A study on maskless selective growth of Mg-doping p-type GaAs using low-energy focused ion beam

Maskless selective growth of Mg-doped GaAs films was performed by using a low-energy (30-200 eV) Mg-Ga focused ion beam (FIB) under the ambient of As4 molecular beam. Under suitable As4 pressure, all samples showed p-type and the carrier concentrations were around 1017 cm−3. We achieved very high sticking coefficient of Mg (kMg of nearly 10−1) compared with the result obtained at Molecular beam epitaxy (MBE) growth (kMg of nearly 10−5). A p-n junction was formed on n+-type GaAs substrate by maskless selective growth. The diode showed typical I-V characteristics and the quality factor (n-value) was approximately 1.75 for the sample grown at 60 eV. These results indicate that this method would be suitable for making maskless selective micro-device fabrication.