In situ Control of Si/Ge Growth on Stripe-Patterned Substrates Using Reflection High-Energy Electron Diffraction and Scanning Tunneling Microscopy

Abstract

Si and Ge growth on the stripe-patterned Si (001) substrates is studied using in situ reflection high-energy electron diffraction (RHEED) and scanning tunneling microscopy (STM). During Si buffer growth, the evolution of RHEED patterns reveals a rapid change of the stripe morphology from a multifaceted “U” to a single-faceted “V” geometry with {119} sidewall facets. This allows to control the pattern morphology and to stop Si buffer growth once a well-defined stripe geometry is formed. Subsequent Ge growth on “V”-shaped stripes was performed at two different temperatures of 520 and 600°C. At low temperature of 520°C, pronounced sidewall ripples are formed at a critical coverage of 4.1 monolayers as revealed by the appearance of splitted diffraction streaks in RHEED. At 600°C, the ripple onset is shifted toward higher coverages, and at 5.2 monolayers dome islands are formed at the bottom of the stripes. These observations are in excellent agreement with STM images recorded at different Ge coverages. Therefore, RHEED is an efficient tool for in situ control of the growth process on stripe-patterned substrate templates. The comparison of the results obtained at different temperature reveals the importance of kinetics on the island formation process on patterned substrates.

Entropy-controlled fully reversible nanostructure formation of Ge on miscut vicinal Si(001) surfaces

“…To monitor the surface evolution during growth and annealing, a multi-chamber molecular beam epitaxy and STM system was employed, allowing surface imaging without breaking ultra-high vacuum conditions [49][50][51]. In our experiments, Ge was deposited at 1 Å/min on Si substrates with various miscut angles and directions at various temperatures between 450 -600°C.…”

Nucleation and epitaxial growth of Ge nanoislands on Si surface prepatterned by ion irradiation

“…Hollows act as the nucleation sites for subsequently grown dots. Since the morphology of Ge QD layer was shown to be strongly dependent upon the pregrowth substrate preparation , new approaches to create preferable nucleation sites at the pregrowth stage may provide better control of fabrication of space‐arranged arrays of QDs.…”

Thermoelectric properties of epitaxial Ge thin films on Si(001) with strong crystallinity dependence

“…1(a) and 1(b)], indicating the formation of {113} Ge facets. 30) In the Two-step-Ge films, streaky spots without chevron patterns were observed, indicating flat surfaces. Figures 1(d)-1(f) show atomic force microscopy (AFM) images of the Ge film surfaces, revealing that the root mean square (RMS) of surface morphologies of the SPE-, MBE-, and Two-step-Ge films are 47.5, 32.9, and 14.6 nm, respectively.…”