Thermodynamic processes on a semiconductor surface during in‐situ multi‐beam laser interference patterning

Abstract

Laser interference has been widely used to produce one-dimensional gratings and more recently has shown great potential for two-dimensional patterning. In this paper, we examine by simulation, its application to in-situ patterning during materials growth. To understand the potential, it is important to study the surface processes resulting from the laser-matter interaction, which have a key influence on the resulting growth mechanisms. In this work, the intensity distribution and the laser-semiconductor interaction resulting from four-beam interference patterns are analysed by numerical simulations. In particular, we derive the time and spatially dependent thermal distribution along with the thermal-induced desorption and surface diffusion. The results provide a crucial understanding of the light-induced thermal profile and show that the surface temperature and the surface adatom kinetics can be controlled by multi-beam pulsed laser interference patterning due to photothermal reactions. The approach has potential as an in-situ technique for the fast and precise nanostructuring of semiconductor material surfaces.

Precise Arrays of Epitaxial Quantum Dots Nucleated by In Situ Laser Interference for Quantum Information Technology Applications

“…Square arrays of symmetric nanoislands with a pattern pitch of 300 nm are clearly observed in Figure a–d, and the cross-sectional profiles along the [100] and [010] directions are shown in Figure g–k. The formation of these nanoislands originates from interference-induced surface diffusion at the nanoscale according to our simulation results Figure b schematically illustrates the formation processes of nanoislands and QDs, where first the laser interference is applied after 1 ML of InAs deposition.…”

“…Because of the absorption of the incident UV pulse, heat is generated at the near surface of the wafer. The temperature rises rapidly (approximately a nanosecond) at the interference maxima, producing a strong lateral thermal gradient that acts as a driving force for atoms to migrate from hot regions (interference maxima) toward adjacent cold regions (interference minima) . This is illustrated by the direction of arrows, where islands then form.…”

“…The laser interference parameters also have a strong impact on the formation of nanoislands and QDs. The interference pattern varies with laser parameters such as angle of incidence, azimuth angle, and polarization state . We have changed the polarization angle of the laser beams to investigate its effects.…”

“…The formation of these nanoislands originates from interference-induced surface diffusion at the nanoscale according to our simulation results. 20 Figure 2b schematically illustrates the formation processes of nanoislands and QDs, where first the laser interference is applied after 1 ML of InAs deposition. Because of the absorption of the incident UV pulse, heat is generated at the near surface of the wafer.…”

“…Since the beams are projected with a large angle of incidence, it is observed that the overlapping area of the four laser beams is reduced to around 3 mm in diameter. The interference pattern from this configuration can be calculated 20 and consists of a 300 nm square grid of high and low laser fluence spots. The nature of the interference pattern has been confirmed by ex situ lithography studies on photoresist using an equivalent geometry.…”