Optical phonon modes, static and high-frequency dielectric constants, and effective electron mass parameter in cubic In2O3

Abstract

A complete set of all optical phonon modes predicted by symmetry for bixbyite structure indium oxide is reported here from a combination of far-infrared and infrared spectroscopic ellipsometry, as well as first principle calculations. Dielectric function spectra measured on high quality, marginally electrically conductive melt grown single bulk crystals are obtained on a wavelength-by-wavelength (a.k.a. point-by-point) basis and by numerical reduction of a subtle free charge carrier Drude model contribution. A four-parameter semi-quantum model is applied to determine all sixteen pairs of infrared-active transverse and longitudinal optical phonon modes, including the high-frequency dielectric constant, ε ∞ = 4.05 ± 0.05. The Lyddane-Sachs-Teller relation then gives access to the static dielectric constant, ε DC = 10.55 ± 0.07. All experimental results are in excellent agreement with our density functional theory calculations and with previously reported values, where existent. We also perform optical Hall effect measurements and determine for the unintentionally doped n-type sample a free electron density of n = (2.81 ± 0.01) × 10 17 cm −3 , mobility of µ = (112 ± 3) cm 2 /(Vs), and an effective mass parameter of (0.208 ± 0.006)m e . Density and mobility parameters compare very well with results of electrical Hall effect measurements. Our effective mass parameter, which is measured independently of any other experimental technique, represents the bottom curvature of the Γ point in In 2 O 3 in agreement with previous extrapolations. We use terahertz spectroscopic ellipsometry to measure the quasistatic response of In 2 O 3 , and our model validates the static dielectric constant obtained from the Lyddane-Sachs-Teller relation.

Growth of twin-free cubic In2O3(111) thick layers on c-plane sapphire substrates by halide vapor phase epitaxy

“…Figure 7 shows that the experimental data were well fitted using w  LO = 47 meV, which is not significantly different from values reported elsewhere. 36,37,41) The electron mobility showed a dependence on optical phonon scattering at about 200 K or higher. However, at lower temperatures, the mobility was limited mainly by ionized impurity scattering (m II ), which decreased with the decreasing temperature.…”

Review—Extremely Thin Amorphous Indium Oxide Transistors

“…where a 0 is the Bohr radius of hydrogen, ɛ r is the relative permittivity, m * e is the electron effective mass, and m e the electron mass. Taking the most reliable known values for bixbyite indium oxide (𝜖 r ≈ 10.55 [48] and m * e = 0.18 m e near the bottom of the conduction band [37,49] ) gives an estimated a* of 3.1 nm. It is likely that the permittivity of amorphous indium oxide differs somewhat, but it is unimportant for this example calculation.…”

“…The effective Bohr radius is given by, $$$$\begin{equation}{a}^* = \frac{{{a}_0{\varepsilon }_{\mathrm{r}}}}{{m_{\mathrm{e}}^*/{m}_{\mathrm{e}}}}\end{equation}$$$$where a 0 is the Bohr radius of hydrogen, ɛ r is the relative permittivity, $$m_{\mathrm{e}}^*$$ is the electron effective mass, and m e the electron mass. Taking the most reliable known values for bixbyite indium oxide (ε r ≈ 10.55 [ 48 ] and $$m_{\mathrm{e}}^* = \ 0.18\,{m}_{\mathrm{e}}$$ near the bottom of the conduction band [ 37,49 ] ) gives an estimated a * of 3.1 nm. It is likely that the permittivity of amorphous indium oxide differs somewhat, but it is unimportant for this example calculation.…”

Высокая Чувствительность Пленок Оксида Индия, Полученных Методом Хлоридной Газофазной Эпитаксии, К Аммиаку

“…При известном значении подвижности электронов (µ = 60 см 2 /(В • с) [3,[5][6][7]17,[29][30][31]) была получена температурная зависимость концентрации электронов (n) и дебаевской длины экранирования (L D ) (рис. 6).…”

“…Оксид индия -металлооксидный полупроводник n-типа проводимости, который за счет оптической прозрачности в видимой области спектра (ширина запрещенной зоны E g = 3.5−3.7 эВ [1][2][3][4][5]), низкой эффективной массы электронов (m n = 0.16−0.25 m [3,6,7]), высокой каталитической активности и проводимости, вызванной наличием дважды ионизированных вакансий кислорода, получил широкое распространение и может быть использован в газовых сенсорах, солнечных элементах, сенсорных и жидкокристаллических дисплеях, тонкопленочных транзисторах, оптоэлектронных и фотоэлектрических устройствах, контактах и диодах Шоттки [1][2][3][4][5][8][9][10][11][12][13][14][15][16][17][18]. Столь обширные и разнообразные области применения чаще относят к In 2 O 3 : Sn [1,3,5,8], в то время как свойства нелегированного In 2 O 3 наиболее активно исследуют для газовой сенсорики [1,2,[11][12][13][14][15][16][17][18].…”