Fabrication of Nitrided Mask on GaAs surface and Its Machinability for STM lithography

Abstract

A nitridation mask on a GaAs surface was prepared using RF-MBE and its machinability by STM lithography was studied. A 5.2 nm thick crystal-like layer was formed at 350°C, and was modified by STM at a sample bias of ±80V with good size reliability, which was sufficiently fine for realizing dislocation-free heteroepitaxial growth of GaAs / Si. The mask was maintained up to 620°C under As flux exposure at 1.5 × 10−4 Pa.

XPS study of nitridation mechanism of GaAs (001) surface by RF‐radical source

“…Then, the surface was nitridated using RF-radical source. During the ignition of the RF-radical source, the substrate was turned over to avoid being damaged by the released materials from the source [8]. The substrate temperature was changed between 346 and 579 o C, while RF power and N 2 flow rate were set to 200 W and 0.6 sccm, respectively.…”

“…The layer is available not only for the buffer layer for c-GaN growth but also passivating the GaAs surface. Therefore, the mechanism of nitridation of GaAs surface has been studied in several institutes [4][5][6][7][8] but there remain unknown parts. For example, the thickness of the layers has not been precisely determined especially in the early stage of nitridation.…”

Influence of substrate temperature on nitridation of (001) GaAs using RF-radical source

“…1. During the ignition of the RF-radical source, the substrate was turned over to avoid being damaged by the released materials from the source [10]. The substrate temperature was changed between 350 and 570 1C, while RF power and N 2 flow were set to 200 W and 0.6 sccm, respectively.…”

“…Though a large lattice mismatch exists between GaN and GaAs, a highquality ultra-thin GaN layer can be reproducibly fabricated by the technique [10,11]. The layer is available not only for protecting but also passivating the GaAs surface.…”

GaAs/c‐GaN/GaAs multi‐layered structure fabricated by using RF‐plasma source nitridation technique

“…3 Results and discussion A RHEED pattern taken after the nitridation showed the same indices as GaAs (001) surface with four fold axis, even though the pattern was scattered. The crystal structure of the nitrided layer was recognized as cubic one with the same lattice space of underlying GaAs layer [4]. It was considered that the lattice of c-GaN layer was expanded because the layer was very thin.…”