Tailoring of Point Defects in Polycrystalline Indium Tin Oxide Films with Postirradiation of Electronegative Oxygen Ions

Abstract

We have developed a state-of-the-art technology to tailor oxygen-related point defects such as oxygen vacancies (V O ) and structural defects of polycrystalline highly conductive Sn-doped In 2 O 3 (ITO) films by a postirradiation of electronegative oxygen (O − ) ions. The intentional oxygen doping that would annihilate V O decreases carrier density (n e ) from 9.3 × 10 20 to 7.1 × 10 20 cm −3 with an increase of Hall mobility (μ H ) from 44 to 51 cm 2 •V −1 •s −1 , and subsequently, n e drastically decreases down to 1.2 × 10 19 cm −3 together with a decrease in μ H owing to a formation of Sn−O neutral complexes with a further increase in the amount of oxygen atoms that should fill the structural defects while retaining their crystal structure. Upon the filling of the structural vacancies, the successful control of intrinsic point defects is probably caused by almost no difference in the ionic radii between In 3+ having six-coordination and Sn 4+ having eight-coordination. The O − -ion-irradiation technology enables one to tailor the physical properties of ITO films over a wide range while retaining the crystal structure of the films.

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

“…The decrease in the energy of interband transitions when eliminating defects in the crystal structure of the films can be explained by the Burstein−Moss shift. The obtained values of the bandgap width are in agreement with the results of [26][27][28].…”

“…The latter depends significantly on crystal structure defects, the number of which is lower in films deposited on substrates with higher temperatures. Annealing in air eliminates oxygen vacancies, which reduces the concentration of charge carriers and therefore the value of E Ŵ g [27,28]. The bandgap width for " indirect" (symmetry forbidden) transitions E indir g varies less due to electron-phonon interactions.…”

Evolution of implicate order from amorphous to polycrystalline Sn-doped In2O3 films determined by in situ two-dimensional X-ray diffraction measurements

“…a-ITO films with a thickness of 50 nm were grown on non-alkali glass (Corning Eagle XG) substrates without intentionally heating the substrates, by reactive plasma deposition with direct-current arc discharge. [26][27][28] The source used was a sintered In 2 O 3 pellet with a SnO 2 content of 5 wt% (corresponding to 4.6 at%). The deposition conditions are described in detail elsewhere.…”

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

“…Последний существенно зависит от дефектов кристаллической структуры, количество которых в плёнках, нанесенных на подложки с большей температурой, меньше. Отжиг на воздухе приводит к устранению кислородных вакансий, что снижает концентрацию носителей заряда, а следовательно, и величину E Ŵ g [27,28]. Ширина запрещённой зоны для " непрямых" (запрещённых по симметрии) переходов E indir g изменяется меньше из-за электрон-фононных взаимодействий.…”

“…Понижение энергии межзонных переходов при устранении дефектов кристаллической структуры плёнок можно объяснить сдвигом Бурштейна−Мосса. Полученные значения ширины запрещённой зоны согласуются с результатами работ [26][27][28].…”