We report on a hybrid method for fabrication of arrays of GaN nanocrystals by low-temperature UHV selective growth on pre-patterned silicon substrates covered by native oxide. Patterning of the substrates was performed by using a gallium focused ion beam (FIB). To get GaN nanocrystals at specific positions, Ga droplets were created at FIB patterned sites by evaporation of Ga atoms at 280 °C substrate temperature first, and then modified by their post-nitridation using an ultra-low energy (50 eV) nitrogen ion–beam at a sample temperature of 200 °C. To get larger arrays of GaN nanocrystals (≈150 nm and 200 nm in diameter), such a sequential process was repeated in several cycles at slightly modified operation conditions. The quality of the nanocrystals was checked by measurement of their photoluminescence properties which proved the occurrence of the peak of a band edge emission at around 367 nm (3.38 eV).

This work was supported by the Technology Agency of the Czech Republic (Grant No. TE01020233), H2020 Twinning programme (project SINNCE, 810626), Grant Agency of the Czech Republic (grant 17-33767L), and MEYS CR (grant No. LQ1601 – CEITEC 2020). We also acknowledge the support by the Grant Agency of the Czech Republic (grant No. 17-21413S).