Ge Nanoislands Grown by Radio Frequency Magnetron Sputtering: Comprehensive Investigation of Surface Morphology and Optical Properties

Abstract

The comprehensive investigation of the effect of growth parameters on structural and optical properties of Si-based single layer Ge nanoislands grown via Stranski-Krastanov mechanism employing radio frequency magnetron sputtering due to its high deposition rate, easy procedure, economical cost, and safety is carried out. The estimated width and height of Ge nanoislands produced by this technique are in the range of ∼8 to ∼30 and ∼2 to 8 nm, respectively. Varieties parameters are manipulated to optimize the surface morphology and structural and optical behavior of Ge nanoislands. The resulted nanoislands are analyzed using various analytical techniques including atomic force microscope, X-ray diffraction, energy dispersive X-ray spectroscopy, room temperature photoluminescence, and Raman spectroscopy. The optimum parameters for growing high quality samples having high number density and homogenous and small size distribution are found to be 400 ∘ C for substrate temperature, 300 sec for deposition time, 10 sccm for Ar flow, and 100 W for radio frequency power. The excellent features of the results suggest that our systematic investigation on the organized growth factors and their effects on surface parameters and photoluminescence emission energy may constitute a basis for the tunable growth of Ge nanoislands (100) nanoislands suitable in nanophotonics.

Structure and optical properties of Ge/Si quantum dots formed by driving the evolution of Ge thin films via thermal annealing

“…7) Samavati and coworkers clarified the effects of some growth parameters, such as substrate temperature, deposition time, working pressure, argon flow rate, and RF power, on the growth of selfassembled Ge=Si nanoislands, and they demonstrated the growth of high-density Ge nanoislands with a base diameter of ∼14 nm directly on a Si(100) wafer at the argon (Ar) flow rate and RF power of 10 sccm and 100 W, respectively. 8,9) Using the annealing technique, Rahim and coworkers realized the growth of Ge=Si islands (100-200 nm in diameter) on a 250-nm-thick Ge film deposited on a Si(100) substrate by RF magnetron sputtering. 10,11) However, the formation and evolution of QDs fabricated by the direct current (DC) magnetron sputtering technique are still not realized because this low-cost growth technique has not yet been widely applied in the field of solid-state QD fabrication.…”

Study on crystal growth of Ge/Si quantum dots at different Ge deposition by using magnetron sputtering technique

“…Abd Rahim et al fabricated low-density Ge QDs with a size of 2.65–3.5 nm by performing rapid annealing (400–800 °C) of amorphous Ge films sputtered at room temperature on Si surfaces 24 . Samavati et al 25 studied the effects of various parameters of RF magnetron sputtering, including substrate temperature, deposition time, Ar flow rate, RF power, working pressure, annealing temperature, and annealing time, on the structure and properties of Si-based Ge quantum dots (Ge/Si QDs). Khelidj et al used magnetron sputtering to grow Ge 1− x Sn x films with potential for CMOS (complementary-metal-oxide-semiconductor) applications and analyzed the nanostructure and electrical properties of the Ge–Sn alloys in these films 26 .…”

“…However, even so, due to the late start of magnetron sputtering in the preparation of QDs, there are still experimental and theoretical blank areas in the growth technics and mechanism. Particularly worth mentioning is that in the reported related research, the formation of QDs was mostly achieved by sputtering thicker (250 nm 24 , 30–66 nm 25 , 100 nm 26 , etc.) Ge films, while excessive deposition thickness means more dislocation defects, which not only reduces the photoelectric properties of films but also adversely affects and interferes structure and performance of surface QDs, which poses a challenge to the device application of QDs.…”

Local structure of amorphous and nanoscale systems by numerical XANES calculations

“…This makes it difficult (and in many cases impossible) to distinguish between metastable structures with similar (by ~0.1-0.2 Å) local bond distances and coordination numbers when only first shell signal is available. In nanomaterials there are added problems of complex nanoscale morphology [36][37][38], possible contribution to the signal from metastable phases [16,39,40] and from surface effects.…”