Electrical and optical properties of amorphous indium oxide

Bellingham, J.R.; Phillips, W. A.; Adkins, C. J.

doi:10.1088/0953-8984/2/28/011

Cited by 239 publications

(143 citation statements)

References 25 publications

Supporting

Mentioning

127

Contrasting

Order By: Relevance

“…There is a clear trend for lower mobilities with increasing carrier concentrations that can be attributed to the effect of ionized impurity scattering. [49][50][51] This effect, as well as the influence of grain boundary scattering has been discussed in comprehensive reviews. 30,39,52 As grain boundary scattering plays an important role in films with doping levels in the low 10 20 cm −3 regime we can conclude, that high mobilities can only be reached if the defect density at the grain boundaries can be kept low.…”

Section: Fig 4 ͑Color Online͒ Mobility Determined Hall Measurementsmentioning

confidence: 99%

Improved electrical transport in Al-doped zinc oxide by thermal treatment

Ruske

Roczen

Lee

et al. 2010

Journal of Applied Physics

176

100

View full text Add to dashboard Cite

A postdeposition thermal treatment has been applied to sputtered Al-doped zinc oxide films and shown to strongly decrease the resistivity of the films. While high temperature annealing usually leads to deterioration of electrical transport properties, a silicon capping layer successfully prevented the degradation of carrier concentration during the annealing step. The effect of annealing time and temperature has been studied in detail. A mobility increase from values of around 40 cm2/Vs up to 67 cm2/Vs, resulting in a resistivity of 1.4×10−4 Ω cm has been obtained for annealing at temperatures of 650 °C. The high mobility increase is most likely obtained by reduced grain boundary scattering. Changes in carrier concentration in the films caused by the thermal treatment are the result of two competing processes. For short annealing procedures we observed an increase in carrier concentration that we attribute to hydrogen diffusing into the zinc oxide film from a silicon nitride barrier layer between the zinc oxide and the glass substrate and the silicon capping layer on top of the zinc oxide. Both are hydrogen-rich if deposited by plasma-enhanced chemical vapor deposition. For longer annealing times a decrease in carrier concentration can occur if a thin capping layer is used. This can be explained by the deteriorating effect of oxygen during thermal treatments which is well known from annealing of uncapped zinc oxide films. The reduction in carrier concentration can be prevented by the use of capping layers with thicknesses of 40 nm or more.

show abstract

Section: Fig 4 ͑Color Online͒ Mobility Determined Hall Measurementsmentioning

confidence: 99%

Improved electrical transport in Al-doped zinc oxide by thermal treatment

Ruske

Roczen

Lee

et al. 2010

Journal of Applied Physics

176

100

View full text Add to dashboard Cite

show abstract

“…[9,[13][14][15][16][17][18][19]24] As the billion-dollar display industry moves forward, the amorphous phase of the complex oxides is favored both for flexible and high-resolution display applications. [13][14][15][16][48][49][50][51][52][53][54][55][56][57][58][59] The unique properties of AOSs were first demonstrated in 1990, [60] and the research area has been growing exponentially since then. Unlike Si-based semiconductors, AOSs were shown to exhibit optical, electrical, thermal, and mechanical properties that are comparable or even superior to those possessed by their crystalline counterparts.…”

mentioning

confidence: 99%

Recent Advances in Understanding the Structure and Properties of Amorphous Oxide Semiconductors

Medvedeva

Buchholz

Chang

2017

Adv Elect Materials

137

144

View full text Add to dashboard Cite

conductivity. [1] Following the discovery of SnO 2 with a similar unique combination of properties, [2] several patents were filed in the 1940s to employ TCOs as antistatic coatings and transparent heaters-long before the discovery of the now well-known Sn-doped In 2 O 3 (ITO) and Al-doped ZnO, [3] widely employed as flat panel display electrodes in the past decades. Despite great technological demand for TCOs [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] and extensive experimental efforts to improve the conductivity via impurity doping, [21,22] to tune the work function and carrier concentration via cation composition, [23][24][25][26][27][28] to achieve two-dimensional transport via heterointerfaces, [29] and to p-dope the oxides toward active layers of transparent electronics, [30][31][32] theoretical understanding of these fascinating materials has lagged behind significantly. The first electronic band structure of ITO was calculated in 2001; [33] the role of native defects in prototype TCOs was understood after 2002; [34][35][36][37] the properties of multi-cation TCOs were first considered in 2004 [37][38][39][40][41][42] followed by modeling of novel TCO hosts [43,44] and spin-dependent transport in transition-metal-doped TCOs; [45] the nature of the band gap in In 2 O 3 was clarified in 2008; [46] and a first highthroughput search for p-type TCOs was performed in 2013. [47] Complex oxides that consist of multiple post-transition metals, such as InGaZnO 4 , have recently become competitive with silicon as the active transistor layer to drive arrays of pixels in large area displays. [9,[13][14][15][16][17][18][19]24] As the billion-dollar display industry moves forward, the amorphous phase of the complex oxides is favored both for flexible and high-resolution display applications. [13][14][15][16][48][49][50][51][52][53][54][55][56][57][58][59] The unique properties of AOSs were first demonstrated in 1990, [60] and the research area has been growing exponentially since then. Unlike Si-based semiconductors, AOSs were shown to exhibit optical, electrical, thermal, and mechanical properties that are comparable or even superior to those possessed by their crystalline counterparts. [48][49][50][51][52][53][54][55][56][57][58] Table 1 summarizes the key physical properties of best-performing crystalline TCOs and AOSs; the differences (or the lack thereof) between the two will be discussed in detail in the respective sections below.

show abstract

“…10, the increase of the free electron density can be attributed to the creation of oxygen vacancies due to relaxation of distorted In-O bonds in the amorphous phase. Since Sn is known not to be electrically active in amorphous ITO [6,24] and does not affect the free electron density, any creation of substitutional Sn in the amorphous film can be neglected.…”

mentioning

confidence: 99%

“…The fast enhancement of the free electron density, N Dr , after the beginning of crystallization (T a ~ 250°C) can be explained by the onset of Sn donor activation [9,10,24] in a growing crystalline phase. However, the SE is sensitive to the free electron density enhancement even in crystalline grains which are electrically insulated or have bad contact to each other [23].…”

mentioning

confidence: 99%

Real-time evolution of the indium tin oxide film properties and structure during annealing in vacuum

Rogozin

Shevchenko

Vinnichenko

et al. 2004

Applied Physics Letters

View full text Add to dashboard Cite

Indium tin oxide (ITO) is widely applied as a transparent conductive oxide coating. A standard and successful industrial route of production is its deposition by magnetron sputtering from a compound (oxide) target [1]. To increase cost efficiency, it would be preferable to sputter reactively from a metal target at sufficiently high partial pressure of oxygen. However, under this condition, a satisfactorily low resistivity of the films cannot readily be obtained, [2] so that a deposition on heated substrates or post-deposition annealing is necessary. So far, the annealing processes for reactively sputtered ITO [3,4] have only been studied for metal-rich films, in contrast to comprehensive studies after magnetron sputtering from ceramic targets [5][6][7][8][9][10]. Moreover, mainly isothermal heat treatment is considered in the literature, although annealing using a temperature ramp is of more relevance for practical application. Several investigations report on real-time in situ monitoring of the ITO film resistivity and reflectivity [9,10], which is used for an indirect characterization of the crystalline structure of the films. This approach requires simplifying assumptions on the linear dependence of the resistivity or reflectivity on the crystalline fraction, and the stability of the film roughness during annealing. Direct investigations of the influence of heat treatment on the ITO film structure are so far limited to post-annealing studies by X-ray diffraction (XRD) and scanning or transmission electron microscopy [3][4][5]7,8,11].Annealing of ITO is known to be very efficient in increasing the carrier concentration. It can be quite reasonably explained by the FrankKöstlin model [12] which accounts for tin donor activation at elevated temperatures. However, this model is valid only for crystalline ITO. The amorphous-to-crystalline transition in ITO during annealing is often assumed as the reason for this activation, but the physics behind the experimental observation is not clear. In the present letter we report the results of a real-time in situ investigation of the film properties and the structure evolution during annealing in vacuum.The films are produced by reactive pulsed middle frequency magnetron sputtering using the facility and procedure described in Ref. 13. The chamber was pumped to a base pressure of 4 × 10 -4 Pa before deposition. The deposition runs were carried out for 2.5 min at an Ar flow of 30 sccm (partial pressure 1.2 Pa) and O 2 flow of 64 sccm (0.3 Pa). The films are grown on Si (100) substrates (24 × 12 × 0.3 mm 3 ) covered with SiO 2 (510 nm), which were not heated externally during deposition. The average thickness of the deposited films is 130 nm. The as-deposited films show no crystalline peaks in the XRD patterns and are considered as amorphous.The post-deposition annealing of identical ITO samples was carried out at two different experimental setups, the ROssendorf Beam Line (ROBL) at the European Synchrotron Radiation Facility in Grenoble, [14] and the ITO deposition facility ...

show abstract

Electrical and optical properties of amorphous indium oxide

Cited by 239 publications

References 25 publications

Improved electrical transport in Al-doped zinc oxide by thermal treatment

Improved electrical transport in Al-doped zinc oxide by thermal treatment

Recent Advances in Understanding the Structure and Properties of Amorphous Oxide Semiconductors

Real-time evolution of the indium tin oxide film properties and structure during annealing in vacuum

Contact Info

Product

Resources

About