Annealing of an AlN buffer layer in N₂–CO for growth of a high-quality AlN film on sapphire

Abstract

The annealing of an AlN buffer layer in a carbon-saturated N 2 -CO gas on a sapphire substrate was investigated. The crystal quality of the buffer layer was significantly improved by annealing at 1650-1700°C. An AlN buffer layer with a thickness of 300 nm was grown by metalorganic vapor phase epitaxy (MOVPE), and was annealed at 1700°C for 1 h. We fabricated a 2-µm-thick AlN layer on the annealed AlN buffer layer by MOVPE. The full widths at half maximum of the (0002)-and (10 12)-plane X-ray rocking curves were 16 and 154 arcsec, respectively, and the threading dislocation density was 4.7 ' 10 8 cm %2 .

Influence of the Strain Relaxation on the Optical Property of AlGaN Quantum Wells

“…A MQW and AlGaN layer were grown on a 1.2 μm AlN template on sapphire by MOCVD. The AlN templates were prepared using DC sputter and HTA method . Details of the AlN growth will be found elsewhere .…”

Annealing of the sputtered AlN buffer layer on r‐plane sapphire and its effect on a‐plane GaN crystalline quality

“…Here, red continuous and blue dotted profiles show the results of 30-nm-thick sp-AlNs on r-sapphire and c-sapphire (as a reference), respectively. Several peaks were attributable to sapphires and sp-AlNs; 2u % 368, 428, 538, and 598 corresponded to the AlN (0002), sapphire (0006), sapphire (20-24), and AlN (11)(12)(13)(14)(15)(16)(17)(18)(19)(20), respectively. The fact that the peak intensity of AlN (0002) increased with increasing T s indicates that better c-axis orientated sp-AlN can be obtained by increasing the T s in the case of sp-AlN on c-sapphire.…”

“…Sputtering is employed as a method of depositing AlN buffer layers because some reports have shown that it is an effective way to improve the crystalline quality of c ‐GaN grown on c ‐plane sapphire ( c ‐sapphire) . Moreover, it has been reported that high‐temperature annealing of an AlN buffer layer produces high‐crystalline‐quality c ‐plane AlN films grown on c ‐sapphire . However, there have been few analogous experiments involving a ‐GaN grown on r ‐sapphire .…”

Influence of Undoped‐AlGaN Final Barrier of MQWs on the Performance of Lateral‐Type UVB LEDs

“…Initially, some other groups also attempted to the crystal growth of bulk AlN single crystal for the applications of AlGaN‐based optoelectronic devices . However, due to the high cost as well as due to the issue of low transmittance of UV‐light through the bulk AlN substrate, several researchers preferred to grow AlGaN‐based UV LEDs either on AlN template on sapphire substrate or to grow it on high‐temperature annealing (HTA) of sputtered AlN template . The crystal quality of AlN template grown on c‐(0001) sapphire substrates was reasonably improved (total‐TDDs ≈5×10 8 cm −2 ) by our group, using a well‐known technique of “ammonia (NH 3 ) pulsed‐flow multilayer (ML) growth.” But still the epitaxial growth of AlGaN on an AlN template can have a lattice mismatch as large as ≈4%, depending on the molar ratio of the Al‐contents in the grown layer.…”