High-Quality 2'' Bulk-Like Free-Standing GaN Grown by HydrideVapour Phase Epitaxy on a Si-doped Metal Organic Vapour Phase Epitaxial GaN Template with an Ultra Low Dislocation Density

Abstract

High-quality 2 00 crack-free free-standing GaN has been attained by hydride vapour phase epitaxial growth on a Si-doped MOVPE GaN template with a low dislocation density and subsequent laser-induced lift-off process. A low value of dislocation density of $2:0 Â 10 7 cm À2 on the Ga-polar face was determined from cathodoluminescence images. X-ray diffraction (XRD) and low-temperature photoluminescence (PL) were exploited to investigate the structural and optical properties of the GaN material. The full width at half maximum value of XRD !-scan of the free-standing GaN is 248 arcsec for the (1 0 1 1 4) reflection. The XRD and low-temperature PL mapping measurements consistently proved the high crystalline quality as well as the lateral homogeneity and the small residual stress of the material. Hence, the bulk-like free-standing GaN studied here is highly advantageous for being used as a lattice-constant and thermal-expansion-coefficient matched substrate for additional strain-free homoepitaxy of III-nitrides-based device heterostructures. The strain-free homoepitaxy will significantly reduce the defect density and thus, an improvement of the device performance and lifetime could be achieved.

Hydride vapor phase epitaxy of GaN boules using high growth rates

“…Freestanding, c-plane GaN substrates can be obtained by separation of the layer from the substrate [7,8] but are still only available in limited quantities. This wafer-by-wafer technique is labor-intensive and due to the heteroepitaxial growth on a foreign substrate TDDs below 10 7 cm À 2 are difficult to achieve [9]. In addition, growth with orientation other than c-direction seems to generally result in high SFDs and TDDs [10,11] making this approach for non-c-plane GaN substrates questionable.…”

Method for modulating the wafer bow of free-standing GaN substrates via inductively coupled plasma etching

“…Normally, a 2 in. free-standing GaN substrate with the bowing radius of 0.6-1.5 m may lead to 500-200 mm height difference between the center and edge of the free-standing GaN substrate, which may even be thicker than the GaN substrate itself [9,10]. This height difference of the free-standing GaN substrates owing to bowing may totally remove the GaN layer around the edge region, but may not polish the GaN layer around the center region during the CMP processes.…”

Polarity dependence of AlN {0 0 0 1} decomposition in flowing H2

“…Recently, many groups have been trying to grow high-quality AlN layers on (0 0 0 1) sapphire substrates by metalorganic vaporphase epitaxy (MOVPE) [9][10][11][12][13][14]. Also, some research groups have reported the growth of thick AlN layers by hydride vapor-phase epitaxy (HVPE) [15][16][17][18][19] with the intention of producing freestanding AlN substrates along similar lines as the fabrication of freestanding GaN substrates [20][21][22][23][24]. However, the optimum temperature for growing high-quality AlN layers by MOVPE or HVPE was found to be higher than 1200 1C [9,13,19], which is above the usual growth temperatures for GaN (1000-1100 1C).…”