(10-11) preferential orientation of polycrystalline AlN grown on SiO2/Si wafers by reactive sputter magnetron technique
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The document discusses the growth of polycrystalline aluminum nitride (AlN) films on silicon wafers using a reactive sputter magnetron technique, focusing on achieving a preferential orientation along the (1 0 ̄1 1) planes. The study employs various analytical methods, including x-ray diffraction and transmission electron microscopy, to characterize the films and highlight challenges due to symmetry issues in the growth chamber. The findings suggest that optimizing the crystal structure of AlN is essential for its applications in semiconductor technologies, especially in deep ultraviolet light-emitting diodes.
![Eur. Phys. J. Appl. Phys. (2016) 74: 10301
DOI: 10.1051/epjap/2016150446
THE EUROPEAN
PHYSICAL JOURNAL
APPLIED PHYSICS
Regular Article
(1 0 ¯1 1) preferential orientation of polycrystalline AlN grown
on SiO2/Si wafers by reactive sputter magnetron technique
Juan B¨urgi1
, Javier Garc´ıa Molleja1,2,a
, Ra´ul Bolmaro1
, Mattia Piccoli3
, Edoardo Bemporad3
, Aldo Craievich4
,
and Jorge Feugeas1
1
Instituto de F´ısica Rosario (CONICET-UNR), 27 de Febrero 210 bis, S2000EZP Rosario, Argentina
2
School of Physics, Yachay Tech, Yachay City of Knowledge, 100119 Urcuqu´ı, Ecuador
3
Department of Engineering, University of Rome “Roma Tre”, Via della Vasca Navale 79, 00146 Rome, Italy
4
Instituto de F´ısica (Universidade de S˜ao Paulo), Rua do Mat˜ao Travessa R 187, CEP05508-090 S˜ao Paulo, Brazil
Received: 28 August 2015 / Received in final form: 13 January 2016 / Accepted: 18 February 2016
Published online: 1 April 2016 – c EDP Sciences 2016
Abstract. Aluminum nitride (AlN) is a ceramic compound that could be used as a processing material
for semiconductor industry. However, the AlN crystalline structure plays a crucial role in its performance.
In this paper, polycrystalline AlN films have been grown onto Si(1 1 1) and Si(1 0 0) (with an oxide native
coverage of SiO2) wafers by RSM (reactive sputter magnetron) technique using a small (5 L) reactor.
The development of polycrystalline AlN films with a good texture along (1 0 ¯1 1) planes, i.e., semi-polar
structure, was shown. Analyses were done using X-ray diffraction in the Bragg-Brentano mode and in the
GIXRD (grazing incidence X-ray diffraction) one, and the texture was determined through pole figures.
The structure and composition of these films were also studied by TEM and EDS techniques. Nevertheless,
the mapping of the magnetic field between the magnetron and the substrate has shown a lack of symmetry
at the region near the substrate. This lack of symmetry can be attributable to the small dimensions of the
chamber, and the present paper suggests that this phenomenon is the responsible for the unusual (1 0 ¯1 1)
texture developed.
1 Introduction
Thin films of III–V compounds are widely investigated
because of the large number of applications on which they
can be involved [1]. These compounds mainly have hcp
crystalline structure. In particular group III nitrides, like
GaN-based materials, spontaneously develop hexagonal
wurtzite structures [2]. GaN (gallium nitride) alloyed with
other nitrides, like InN (indium nitride) and AlN (alu-
minum nitride), was successfully explored as a solid-state
lighting material and in high power and high frequency
electronics [3,4]. Nevertheless, the efficiency and the fre-
quency range of light-emitting diodes (LED) and laser
diodes (LD), which can be primarily selected by the com-
pound nature, also can be affected by the presence of pre-
ferred crystal orientation [5]. An (0 0 0 1) orientation has
a polar behavior, meanwhile a (1 0 ¯1 0) has a non polar
one [6]. The polar nature of wurtzite, for example, allows
the generation of strong electric fields due to the disconti-
nuities in the lattice induced by spontaneous piezoelectric
polarization [7]. On the other hand, AlN is one of the
a
e-mail: garciamolleja@ifir-conicet.gov.ar
most promising materials in LED applications in the deep
ultraviolet (DUV) region [8,9].
AlN can have crystalline structures such as zinc-blend
or wurtzite types, although the thermodynamically stable
phase is only the wurtzite one [10]. To allow the explo-
ration of AlN as a material for DUV-LED applications,
research was directed to obtain crystals with non-polar or
semi-polar orientations [11]. The basis for the experiments
was mainly the epitaxial growth of AlN on top of single-
crystals [12–14]. Silicon carbide (SiC) has a hcp crystalline
structure with lattice constants closely related to AlN, and
it is useful material for hetero-epitaxial growth of AlN.
In addition, SiC presents polytypism giving the chance
to select the polytype, with 2H (wurtzite), 4H or 6H, as
the final surface crystal structure. Furthermore, the final
AlN structure will depend on the mechanisms of grow-
ing compound. Plasma-assisted molecular beam epitaxy
(PAMBE), for example, have been used to grow (1 0 ¯1 0)
AlN on (1 0 ¯1 0) SiC and (0 0 0 1) AlN on (0 0 0 1) SiC [15],
and (1 1 ¯2 0) AlN on (1 1 ¯2 0) SiC [16].
The previous description concerns to singlecrystalline
thin film growth, but polycrystalline thin films can also
be of interest, provided that a high degree of preferential
crystal orientation (i.e., texture) is achieved [17,18]. Those
10301-p1](https://image.slidesharecdn.com/2016brgij-160620221237/85/10-11-preferential-orientation-of-polycrystalline-AlN-grown-on-SiO2-Si-wafers-by-reactive-sputter-magnetron-technique-1-320.jpg)
(10-11) preferential orientation of polycrystalline AlN grown on SiO2/Si wafers by reactive sputter magnetron technique
- 1. Eur. Phys. J. Appl. Phys. (2016) 74: 10301 DOI: 10.1051/epjap/2016150446 THE EUROPEAN PHYSICAL JOURNAL APPLIED PHYSICS Regular Article (1 0 ¯1 1) preferential orientation of polycrystalline AlN grown on SiO2/Si wafers by reactive sputter magnetron technique Juan B¨urgi1 , Javier Garc´ıa Molleja1,2,a , Ra´ul Bolmaro1 , Mattia Piccoli3 , Edoardo Bemporad3 , Aldo Craievich4 , and Jorge Feugeas1 1 Instituto de F´ısica Rosario (CONICET-UNR), 27 de Febrero 210 bis, S2000EZP Rosario, Argentina 2 School of Physics, Yachay Tech, Yachay City of Knowledge, 100119 Urcuqu´ı, Ecuador 3 Department of Engineering, University of Rome “Roma Tre”, Via della Vasca Navale 79, 00146 Rome, Italy 4 Instituto de F´ısica (Universidade de S˜ao Paulo), Rua do Mat˜ao Travessa R 187, CEP05508-090 S˜ao Paulo, Brazil Received: 28 August 2015 / Received in final form: 13 January 2016 / Accepted: 18 February 2016 Published online: 1 April 2016 – c EDP Sciences 2016 Abstract. Aluminum nitride (AlN) is a ceramic compound that could be used as a processing material for semiconductor industry. However, the AlN crystalline structure plays a crucial role in its performance. In this paper, polycrystalline AlN films have been grown onto Si(1 1 1) and Si(1 0 0) (with an oxide native coverage of SiO2) wafers by RSM (reactive sputter magnetron) technique using a small (5 L) reactor. The development of polycrystalline AlN films with a good texture along (1 0 ¯1 1) planes, i.e., semi-polar structure, was shown. Analyses were done using X-ray diffraction in the Bragg-Brentano mode and in the GIXRD (grazing incidence X-ray diffraction) one, and the texture was determined through pole figures. The structure and composition of these films were also studied by TEM and EDS techniques. Nevertheless, the mapping of the magnetic field between the magnetron and the substrate has shown a lack of symmetry at the region near the substrate. This lack of symmetry can be attributable to the small dimensions of the chamber, and the present paper suggests that this phenomenon is the responsible for the unusual (1 0 ¯1 1) texture developed. 1 Introduction Thin films of III–V compounds are widely investigated because of the large number of applications on which they can be involved [1]. These compounds mainly have hcp crystalline structure. In particular group III nitrides, like GaN-based materials, spontaneously develop hexagonal wurtzite structures [2]. GaN (gallium nitride) alloyed with other nitrides, like InN (indium nitride) and AlN (alu- minum nitride), was successfully explored as a solid-state lighting material and in high power and high frequency electronics [3,4]. Nevertheless, the efficiency and the fre- quency range of light-emitting diodes (LED) and laser diodes (LD), which can be primarily selected by the com- pound nature, also can be affected by the presence of pre- ferred crystal orientation [5]. An (0 0 0 1) orientation has a polar behavior, meanwhile a (1 0 ¯1 0) has a non polar one [6]. The polar nature of wurtzite, for example, allows the generation of strong electric fields due to the disconti- nuities in the lattice induced by spontaneous piezoelectric polarization [7]. On the other hand, AlN is one of the a e-mail: garciamolleja@ifir-conicet.gov.ar most promising materials in LED applications in the deep ultraviolet (DUV) region [8,9]. AlN can have crystalline structures such as zinc-blend or wurtzite types, although the thermodynamically stable phase is only the wurtzite one [10]. To allow the explo- ration of AlN as a material for DUV-LED applications, research was directed to obtain crystals with non-polar or semi-polar orientations [11]. The basis for the experiments was mainly the epitaxial growth of AlN on top of single- crystals [12–14]. Silicon carbide (SiC) has a hcp crystalline structure with lattice constants closely related to AlN, and it is useful material for hetero-epitaxial growth of AlN. In addition, SiC presents polytypism giving the chance to select the polytype, with 2H (wurtzite), 4H or 6H, as the final surface crystal structure. Furthermore, the final AlN structure will depend on the mechanisms of grow- ing compound. Plasma-assisted molecular beam epitaxy (PAMBE), for example, have been used to grow (1 0 ¯1 0) AlN on (1 0 ¯1 0) SiC and (0 0 0 1) AlN on (0 0 0 1) SiC [15], and (1 1 ¯2 0) AlN on (1 1 ¯2 0) SiC [16]. The previous description concerns to singlecrystalline thin film growth, but polycrystalline thin films can also be of interest, provided that a high degree of preferential crystal orientation (i.e., texture) is achieved [17,18]. Those 10301-p1