Effect of nanoscale surface morphology on the phase stability of 3C-AlN films on Si(111)

Abstract

In this work, we report on the stabilization of 3C-AlN polytype by molecular-beam epitaxy ͑MBE͒ on 3C-SiC/ Si͑111͒ pseudosubstrates. The main purpose of the present studies is to analyze the mechanisms forcing the epitaxy of the 3C-AlN at typical MBE conditions. The forces driving the cubic polytype formation have been considered including supersaturation, macroscopic stress, interfacial energy, and interface morphology. We conclude that the growth of 3C-AlN phase can be stabilized on the "rough" 3C-SiC͑111͒ surface by the polytype replication due to the lateral character of the nucleation and the reduction in the total energy of the film provided by periodical undulations of the template surface.

Evaluation of AlN material properties through vibration analysis of thin membranes

“…An in vacuo quality factor Q 10 = ω 10 /Δω 10 ~ (4-8)x10 3 was obtained for the (1,0) mode indicating negligible deviations of the material and geometrical properties over the membrane. It is also important for the analysis that if the (1,0) mode is selectively excited using the external source, it is sufficient to consider only the deflection of the membrane centre, therefore, reducing the vibration analysis to the 1D case of forced vibrations with viscous damping.…”

“…A dielectric constant of ε ~ 8.5 that is hundred times smaller than that for PbZr x Ti 1-x O 3 films and Young's modulus of E ~ 354 GPa make AlN also a competitive material for micro-and nano-electromechanical system actuation, in spite of a much smaller d 33 piezoelectric coefficient. In addition, AlN textured deposit possesses tunable residual strain, which can be orders of magnitude lower as those existing in single crystalline epitaxial structures [2,3].…”

Wet chemical etching of AlN in KOH solution

“…AlN layers were deposited on sapphire and silicon substrates (i) by metal organic chemical vapor deposition (MOCVD) [8], (ii) by molecular beam epitaxy (MBE) [5,7] and (iii) reactive sputter deposition [6]. Figure 1 shows the atomic force microscopy (AFM) images of representative samples, which were used for the etching experiments.…”

Growth of atomically smooth cubic AlN by molecular beam epitaxy

“…The surface roughness is of great importance for nanoscale devices as high roughness can lead to shortcuts in electronic devices and broadening of confined electronic states of low dimensional structures. In the past cubic AlN has shown considerable roughness and a tendency to form hexagonal inclusions [2,3]. In this contribution we report on the PAMBE growth of atomically flat c-AlN layers with a surface roughness around 0.3 nm RMS.…”