Ammonia assisted low temperature growth of In2O3 (111) epitaxial films on c-sapphire substrates by chemical vapor deposition technique

Abstract

The authors report the growth of bixbyite In2O3 (111) epitaxial layers on c-plane sapphire substrates by a chemical vapor deposition route, in which growth takes place under the flow of oxygen and ammonia in a furnace. Indium metal is used as the source for indium. It has been found that In2O3 films with high epitaxial quality can be grown by optimizing the growth temperature and the flow rate of NH3. Ammonia plays a catalytic role in the growth process. At growth temperatures less than 550 °C, inclusion of a rhombohedral phase, which is known to be thermodynamically stable only at high pressure, has been detected in the film. X-ray photoelectron spectroscopy does not show the presence of nitrogen in these films. An x-ray diffraction study reveals a sharp increase of disorder in these films as the growth temperature increases beyond 550 °C. The bandgap of the material is also found to decrease with the increase of disorder.

Strain-induced variation of bandgap in (111) In2O3 epitaxial films grown on c-sapphire substrates by a pulsed laser deposition technique

“…Note that the In 2 O 3 (4 40) plane has a three-fold symmetry about the (111) direction. The appearance of six peaks thus suggests that two types of triangular domain, in-plane rotated by 60 • , coexist in the film [11]. It should be mentioned that similar ϕ-scans are obtained for all samples investigated here.…”

“…Indium interstitials in the presence of oxygen vacancies are also shown to act as shallow donors in the material [22]. A large variation of bandgap values ranging from 3.3 to 3.8 eV has been reported for the material [1,11], the reason for which is not fully understood at this moment. Photoabsorption is the technique most frequently used to estimate the bandgap of a semiconductor.…”

“…The most commonly observed phase of In 2 O 3 is bodycentered cubic bixbyite. There are reports of epitaxial growth of In 2 O 3 films on substrates such as Y-stabilized ZrO 2 , and α-Al 2 O 3 (0001) using various techniques such as chemical vapor deposition (CVD) [11], low pressure CVD [12], pulsed electron deposition [13], molecular beam epitaxy [14][15][16], and pulsed laser deposition (PLD) [17,18]. Grown samples are often found to be unintentional n-type doped.…”

Formation of In-=SUB=-2-=/SUB=-O-=SUB=-3-=/SUB=- films by magnetron sputtering on Al-=SUB=-2-=/SUB=-O-=SUB=-3-=/SUB=- (012) substrates

“…Depending on the chosen crystal-lattice orientation of the sapphire substrate cut plane and the sputtering method, both polycrystalline and epitaxial films can be obtained. And while the number of works devoted to epitaxial films on sapphire substrates is quite large [6][7][8][9][10], the amount of studies devoted to polycrystalline films is small. It should be noted that depending on the method and modes of production, the surface structure of the films may be different [11].…”

Формирование плёнок In-=SUB=-2-=/SUB=-O-=SUB=-3-=/SUB=- методом магнетронного напыления на подложках Al-=SUB=-2-=/SUB=-O-=SUB=-3-=/SUB=- (012)

“…В зависимости от выбранной кристаллографической ориентации плоскости среза сапфировой подложки и метода напыления возможно получение как поликристаллических, так и эпитаксиальных плёнок. И если количество работ, посвящённых эпитаксиальным плёнкам на сапфировых подложках, достаточно велико [6][7][8][9][10], то число работ, посвященных поликристаллическим плёнкам, мало. Отметим, что в зависимости от метода и режимов получения структура поверхности плёнок может быть различной [11].…”