Sputtering of (001)AlN thin films: Control of polarity by a seed layer

Abstract

The authors report on the ability to control the polarity of sputter deposited AlN(001) thin films using seed layers. Reactive sputter deposition leads to N-polarity on any substrate hitherto applied, i.e., Si(111), sapphire, SiO2, and polycrystalline metals such as Pt(111), Mo(110), and W(110). A site-controlled polarity allows for an efficient excitation of shear modes of surface, bulk, and Lamb waves by interdigitated electrodes. The authors were able to introduce the Al-polarity through a metal-organic chemical-vapor deposition seed layer. By subsequently patterning the substrate surface, it was possible to define the desired film polarity of sputter deposited AlN film. Polarities were determined by selective etching with KOH solutions and by piezoresponse force microscopy.

Abnormal Grain Growth in AlScN Thin Films Induced by Complexion Formation at Crystallite Interfaces

“…They showed that the piezoelectric properties increased with the absolute value of the substrate bias voltage (it is negative) up to a given saturation, independently of which parameter was changed to get a higher value of the self‐bias voltage. These experiments show also that a defined polar texture (N‐polar in this case) requires a minimal ion bombardment. The bias effect on the texture was also confirmed by the finding of Takikawa et al: vacuum arc deposition without bias produced (100) oriented films, and a transition to (0001)‐orientation was observed with increased negative substrate bias voltage.…”

Polarity-inverted ScAlN film growth by ion beam irradiation and application to overtone acoustic wave (000-1)/(0001) film resonators

“…15 Milyutin et al demonstrated the growth of the polarity-inverted sputter-deposited AlN film by inserting thin metal-organic chemical-vapor deposited AlN under-layer. 16 However, the multilayer polarity-inverted structure, such as that shown in Fig. 1(c), has not been obtained by these polarity inversion techniques that utilize the properties of the under-layer surface, because the polarity of the second and subsequent layers cannot be controlled.…”

“…13 The insertion of a buffer layer is one of the approaches to obtaining polarity inversion in III-nitride films. [14][15][16] AlN epitaxial buffer layer between a (0001) GaN layer and an Al 2 O 3 substrate leads to polarity inversion of the epitaxial GaN layer. 14 Larson III et al reported the polarity inversion of a (0001) AlN film by using a clean Al under-layer.…”

Metastable ScAlN and YAlN Thin Films Grown by Reactive Magnetron Sputter Epitaxy

“…As mentioned in the introduction, for AlN is in the range of [23]. ach atomic layer consists of only one type of atoms, the synthesized either Al or N, so called growth polarity determines the direction of the previously m Different approaches and possible explanations on how to control the polarity, such as substrate and seed layer choice [24] are of great interest. pressures and temperatures AlN can also be synthesized in a cubic phase, for example as epitaxial films onto Si substrates superlattice [30] In my research, the optimizing growth parameters and as reference during the characterization.…”