Dewetting behavior of Ge layers on SiO2 under annealing

Abstract

the solid-state dewetting phenomenon in Ge layers on Sio 2 is investigated as a function of layer thickness d Ge (from 10 to 86 nm) and annealing temperature. The dewetting is initiated at about 580-700 °C, depending on d Ge , through the appearance of surface undulation leading to the particle formation and the rupture of Ge layers by narrow channels or rounded holes in the layers with the thicknesses of 10-60 and 86 nm, respectively. The channel widths are significantly narrower than the distance between the particles that causes the formation of thinned Ge layer areas between particles at the middle dewetting stage. the thinned areas are then agglomerated into particles of smaller sizes, leading to the bimodal distributions of the Ge particles which are different in shape and size. The existence of a maximum in the particle pair correlation functions, along with the quadratic dependence of the corresponding particle spacing on d Ge , may indicate the spinodal mechanism of the dewetting in the case of relatively thin Ge layers. Despite the fact that the particle shape, during the solid-state dewetting, is not thermodynamically equilibrium, the use of the Young's equation and contact angles allows us to estimate the particle/substrate interface energy.

Solid-State Dewetting Dynamics of Amorphous Ge Thin Films on Silicon Dioxide Substrates

“…The evolution with the annealing temperature of surface morphology of metastable a-Ge samples into crystalline Ge islands shows marked differences with respect to the c-Ge film dewetting [ 24 ]. Comparing the dewetting dynamics for similar thickness of crystalline SiGe [ 3 , 12 , 25 ], crystalline Ge [ 24 ] with that of amorphous Ge [ 9 ], we observe that for this latter case the temperature range for obtaining well separated islands is in the 600 °C range against 700 °C or more for the former cases.…”

“…The great variability is attributed to sample preparation, layer thicknesses, interfaces, oxygen contamination and other extrinsic effects. In particular, the high temperature for the initiation of crystallization and dehumidification of the thin layers of a-Ge has been attributed to the presence of oxygen contamination on the surface [ 25 ]. Recent results by Camara et al [ 27 ] confirm this interpretation.…”

“…The whole process is therefore determined by the nucleation of crystalline seeds in the a-Ge and the subsequent increase in size due to mass transport from the destabilized 2D film. Despite the central role of crystallization during annealing for dewetting, this point was not thoroughly addressed in past reports on the same topic [ 9 , 25 ].…”

Broadband Antireflection Coatings Made of Resonant Submicron- and Micron-Sized SiGe Particles Grown on Si Substrates

“…Such conditions take place for SiGe particles, in our case, due to their AR values. It is important to note that the similar AR values are quite common for particles that are naturally formed as a result of the liquid-state [48] and solid-state dewetting phenomenon [27], [32], [47].…”

“…The most technologically simple approaches are based on the self-organization of continuous surface layers through their agglomeration into compact particles by means of the dewetting phenomenon. This phenomenon was best studied for Si [23]- [29] and Ge [24], [30]- [32] layers on SiO2. The solidstate dewetting phenomenon has recently been observed for Ge layers on Si substrates [33], [34].…”