Characterisation of nitride thin films by electron backscattered diffraction

SummaryThin films incorporating GaN, InGaN and AlGaN are presently arousing considerable excitement because of their suitability for UV and visible light-emitting diodes and laser diodes. However, because of the lattice mismatch between presently used substrates and epitaxial nitride thin films, the films are of variable quality.In this paper we describe our preliminary studies of nitride thin films using electron backscattered diffraction (EBSD). We show that the EBSD technique may be used to reveal the relative orientation of an epitaxial thin film with respect to its substrate (a 90 ° rotation between a GaN epitaxial thin film and its sapphire substrate is observed) and to determine its tilt (a GaN thin film was found to be tilted by 13 ± 1 ° towards [10 0] GaN ), where the tilt is due to the inclination of the sapphire substrate (cut off-axis by 10 ° from (0001) sapphire towards (10 0) sapphire ). We compare EBSD patterns obtained from As-doped GaN films grown by plasma-assisted molecular beam epitaxy (PA-MBE) with low and high As 4 flux, respectively. Higher As 4 flux results in sharper, better defined patterns, this observation is consistent with the improved surface morphology observed in AFM studies. Finally, we show that more detail can be discerned in EBSD patterns from GaN thin films when samples are cooled.

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“…Figure 2 shows EBSD patterns from a GaN thin film and its sapphire substrate (Trager‐Cowan et al. , 2001).…”

Section: Resultsmentioning

confidence: 99%

“…Orientation of a GaN epilayer with respect to a sapphire substrate Figure 2 shows EBSD patterns from a GaN thin film and its sapphire substrate (Trager-Cowan et al , 2001). The 3 µ m thick GaN thin film was grown by metalorganic chemical vapour deposition.…”

Section: Resultsmentioning

confidence: 99%

Characterization of nitride thin films by electron backscatter diffraction

Trager-Cowan

Sweeney

Hastie

et al. 2002

Journal of Microscopy

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“… solidified material and its substrate, for example, in welding (Wright & Cotton, 1995; Katayama et al ., 1999; Nelson et al , 1999a,b; Bezençon et al ., 2003; Brooks et al ., 2003; Iamboliev et al ., 2003; Robino et al ., 2003; Kostrivas & Lippold, 2004), precipitates and matrix, for example, in hydrided Zr alloy (Une et al ., 2004; Une & Ishimoto, 2006), in an austenitic stainless steel (Lewis et al ., 2006), in a sintered [Ti alloy + TiB] metal matrix composite (Feng et al ., 2005) and even in meteoritic minerals (Geist et al ., 2005), parent and product phases in discontinuous precipitation, for example, in Cu alloys (Li et al ., 1994; Mangan & Shiflet, 1997) and in Ni base alloy (Lavigne et al , 2001, 2004; Sennour et al ., 2004), successively deposited thin film layers, for example, on sapphire (Cain & Lange, 1994; Cain et al ., 1995; Loloee et al ., 2001; Trager‐Cowan et al ., 2001), on polycrystalline Cu (Missiaen et al ., 2005), on GaN (Davydov et al ., 2004) and on Ti oxide (Cosandey, 1997; Cosandey et al ., 2001), product matrix phases formed by solid‐state phase transformation (e.g. Miyamoto et al ., 2003): a number of references concerning both diffusional and martensitic phase transformations in ferrous, non‐ferrous and intermetallic alloys are given in Gourgues‐Lorenzon (2007). …”

Section: Brief State‐of‐the‐art Summary Of Applications Of Ebsd To Phmentioning

confidence: 99%

Application of electron backscatter diffraction to the study of phase transformations: present and possible future

Gourgues-Lorenzon

2009

Journal of Microscopy

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SummaryThis paper first underlines the main advantages, use and limitations of the electron backscatter diffraction technique from the viewpoint of phase transformations. To get a deeper understanding of physical mechanisms involved in phase transformations, several evolutions are now in progress to get an insight into both three-dimensional and real-time information. Two of them, in particular, improvement of data collection versus improvement of data processing are discussed in the second part of this paper.

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“…13,14 In this study, the growth condition dependences of the metastable ZB-phase inclusion in Àc-plane InGaN/GaN multiple quantum wells (MQWs) are elucidated by using the electron backscatter diffraction (EBSD) measurements. 15,16 Several methods to suppress the ZB-phase inclusion are proposed. Finally, the almost pure WZ-phase MQWs with smooth surface are realized.…”

mentioning

confidence: 99%

Suppression of metastable-phase inclusion in N-polar (0001¯) InGaN/GaN multiple quantum wells grown by metalorganic vapor phase epitaxy

Shojiki

Choi

Iwabuchi

et al. 2015

Applied Physics Letters

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The metastable zincblende (ZB) phase in N-polar (0001¯) (−c-plane) InGaN/GaN multiple quantum wells (MQWs) grown by metalorganic vapor phase epitaxy is elucidated by the electron backscatter diffraction measurements. From the comparison between the −c-plane and Ga-polar (0001) (+c-plane), the −c-plane MQWs were found to be suffered from the severe ZB-phase inclusion, while ZB-inclusion is negligible in the +c-plane MQWs grown under the same growth conditions. The ZB-phase inclusion is a hurdle for fabricating the −c-plane light-emitting diodes because the islands with a triangular shape appeared on a surface in the ZB-phase domains. To improve the purity of stable wurtzite (WZ)-phase, the optimum conditions were investigated. The ZB-phase is dramatically eliminated with decreasing the V/III ratio and increasing the growth temperature. To obtain much-higher-quality MQWs, the thinner InGaN wells and the hydrogen introduction during GaN barriers growth were tried. Consequently, MQWs with almost pure WZ phase and with atomically smooth surface have been demonstrated.

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Characterisation of nitride thin films by electron backscattered diffraction

Cited by 12 publications

References 6 publications

Characterization of nitride thin films by electron backscatter diffraction

Characterization of nitride thin films by electron backscatter diffraction

Application of electron backscatter diffraction to the study of phase transformations: present and possible future

Suppression of metastable-phase inclusion in N-polar (0001¯) InGaN/GaN multiple quantum wells grown by metalorganic vapor phase epitaxy

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