Strong photoluminescence emission from polycrystalline GaN layers grown on W, Mo, Ta, and Nb metal substrates

Yamada, K.; Asahi, H.; Tampo, Hitoshi; Imanishi, Yasuo; Ohnishi, K.; Asami, K.

doi:10.1063/1.1371528

Cited by 51 publications

(42 citation statements)

References 13 publications

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“…7 Device quality epitaxial GaN films have usually been grown using metal organic chemical vapor deposition ͑MOCVD͒ or molecular beam epitaxy ͑MBE͒ techniques. 1,8 However, owing to their enormous application potential, there has recently been increasing interest in polycrystalline GaN films grown by MBE, [9][10][11][12][13][14] MOCVD, [15][16][17][18] and sputtering. [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36] Polycrystalline, 19 nanocrystalline, 20 and amorphous 37 GaN have also shown good luminescence characteristics.…”

Section: Introductionmentioning

confidence: 99%

Spectroscopic ellipsometry studies of GaN films deposited by reactive rf sputtering of GaAs target

Biswas

Bhattacharyya

Sahoo

et al. 2008

Journal of Applied Physics

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Properties of InxGa1−xN films in terahertz range Appl. Phys. Lett. 100, 071913 (2012) Thermal carrier emission and nonradiative recombinations in nonpolar (Al,Ga)N/GaN quantum wells grown on bulk GaN J. Appl. Phys. 111, 033517 (2012) Surface depletion mediated control of inter-sub-band absorption in GaAs/AlAs semiconductor quantum well systems Appl. Phys. Lett. 100, 051110 (2012) High-Q optomechanical GaAs nanomembranes Appl. Phys. Lett. 99, 243102 (2011) Mg-induced terahertz transparency of indium nitride films Appl. Phys. Lett. 99, 232117 (2011) Additional information on J. Appl. Phys. GaN films have been deposited by reactive rf sputtering of GaAs target in 100% nitrogen ambient on quartz substrates at different substrate temperatures ranging from room temperature to 700°C. A series of films, from arsenic-rich amorphous to nearly arsenic-free polycrystalline hexagonal GaN, has been obtained. The films have been characterized by phase modulated spectroscopic ellipsometry to obtain the optical parameters, viz., fundamental band gap, refractive index, and extinction coefficient, and to understand their dependence on composition and microstructure. A generalized optical dispersion model has been used to carry out the ellipsometric analysis for amorphous and polycrystalline GaN films and the variation of the optical parameters of the films has been studied as a function of substrate temperature. The refractive index values of polycrystalline films with preferred orientation of crystallites are slightly higher ͑2.2͒ compared to those for amorphous and randomly oriented films. The dominantly amorphous GaN film shows a band gap of 3.47 eV, which decreases to 3.37 eV for the strongly c-axis oriented polycrystalline film due to the reduction in amorphous phase content with increase in substrate temperature.

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Section: Introductionmentioning

confidence: 99%

Spectroscopic ellipsometry studies of GaN films deposited by reactive rf sputtering of GaAs target

Biswas

Bhattacharyya

Sahoo

et al. 2008

Journal of Applied Physics

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“…GaN layers are grown on totally different structures ranging from silica quartz [6][7][8], the group I metals, e.g. silver [9], or refractory metals, such as W, Mo, Ta and Nb [10]. The two techniques were used: by plasma-assisted MBE (PA MBE) and MOVPE.…”

Section: Introductionmentioning

confidence: 99%

“…The two techniques were used: by plasma-assisted MBE (PA MBE) and MOVPE. In case of the deposition of GaN layers by PA MBE, the growth was carried out at very low temperature, about 400 o C [10]. Initially the 3nm thick GaN buffer layer was grown.…”

Section: Introductionmentioning

confidence: 99%

TEM investigations of GaN layers grown on silicon and sintered GaN nano‐ceramic substrates

Borysiuk¹,

Caban

Strupiński

et al. 2007

Cryst. Res. Technol.

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GaN nano-ceramics were analyzed using transmission electron microscopy (TEM), showing that these ceramics are characterized by highly disoriented grains of the linear size of 100-150 nm. These GaN ceramics were used as substrates for GaN epitaxy in standard MOVPE conditions. For the comparison, MOVPE GaN layers on silicon substrates were grown using similar conditions. It is shown that MOVPE growth of GaN layers is highly anisotropic for both cases. However, the disorientation of the highly mismatched GaN layer on silicon is different from that characterizing GaN layer deposited on the ceramic substrate. In the latter case the disorientation is much higher, and three dimensional in nature, causing creation of polycrystalline structure having large number of the dislocations. In the case of the GaN layer grown on the silicon substrate the principal disorientation is due to rotation around c-axis, causing creation of mosaic structure of edge dislocations. Additionally, it is shown that the typical grain size in AlN nucleation layer on Si is smaller, of order of 20 nm. These two factors contribute to pronounced differences in later stage of the growth of GaN layer on the ceramic. Due to high growth anisotropy an appropriately thick GaN layer can, eventually, develop flat surfaces suitable for construction of optoelectronic and electronic structures. As shown by the TEM data, this can be achieved only at the cost of creation of the relatively large density of dislocations and stacking faults. The latter defects were not observed for the GaN growth on Si substrates.

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“…On the contrary, the use of metal substrates will avoid these problems. Recently, we have reported the growth of GaN on metal substrates and the strong band-edge photoluminescence (PL) emission without deep-level emission in spite of the polycrystalline nature of GaN on metal substrates [6].…”

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confidence: 99%

Field Emission from Polycrystalline GaN Grown on Mo Substrate

Yamanaka

Tampo

Yamada

et al. 2002

phys. stat. sol. (c)

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Strong photoluminescence emission from polycrystalline GaN layers grown on W, Mo, Ta, and Nb metal substrates

Cited by 51 publications

References 13 publications

Spectroscopic ellipsometry studies of GaN films deposited by reactive rf sputtering of GaAs target

Spectroscopic ellipsometry studies of GaN films deposited by reactive rf sputtering of GaAs target

TEM investigations of GaN layers grown on silicon and sintered GaN nano‐ceramic substrates

Field Emission from Polycrystalline GaN Grown on Mo Substrate

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