Development of GaN substrate with a large diameter and small orientation deviation

Abstract

In this study, we demonstrated a very large freestanding GaN crystal with a diameter of 175 mm developed by the “tiling technique”. The technique merges small multiple seed wafers with a thick GaN layer grown by hydride vapor phase epitaxy. To the best of our knowledge, it is the largest GaN crystal ever reported. Its orientation deviation could be the same as those of applied individual seeds by using the starting substrate, which was prepared by binding all the seeds on a base plate with a high temperature adhesive. Scrupulous attention was required to select the materials. Furthermore, we were able to grow GaN with hydride vapor phase epitaxy on a high‐quality GaN substrate, which was prepared by an Na‐flux method, with no crystal deteriorations. Through the fusion of the above results, the ideal GaN substrates can be realized. Example of a freestanding GaN crystal with a diameter of 175 mm developed by the “tiling technique”.

Evolution of V-pits in the ammonothermal growth of GaN on HVPE-GaN seeds

“…Nowadays, hydride vapor phase epitaxy (HVPE) is primarily the growth method for commercial bulk GaN substrates because of its high growth rate (up to hundreds of micrometers per hour), and the ability to grow large-size wafers (up to Φ175 mm). 9–11 HVPE is known to be a suitable growth technique for the fabrication of free-standing GaN wafers due to its high growth rate and high quality. However, the generation of pit-type defects in the growth is still an unresolved question.…”

Floral design GaN crystals: low-resistive and low-dislocation-density growth by oxide vapor phase epitaxy

“…[16][17][18][19] Further, to increase the diameter, 6-7 inch GaN wafers have been achieved by the HVPE and Na-flux methods. 13,[20][21][22] We have been developing the oxide vapor phase epitaxy (OVPE) method to manufacture high-performance, low-cost GaN wafers. 23) This method can be used to manufacture large bulk GaN crystals with a simple apparatus for long-term growth, since no NH 4 Cl is generated as a solid by-product, unlike the case with the HVPE method, which is the mainstream GaN manufacturing technology.…”

Growth and doping of bulk GaN by hydride vapor phase epitaxy*

“…[14,15] Nowadays, commercial bulk GaN substrates are primarily produced by hydride vapor phase epitaxy (HVPE) because of its high growth rate (up to hundreds of micrometers per hour) and the ability to grow large size wafer (up to Φ175 mm). [16][17][18] The carrier concentration of undoped GaN grown by HVPE is commonly on the order of 10 16 -10 17 cm −3 , [19] which is unsuitable for GaN-based devices. For example, high conductive GaN substrates (n > 1 × 10 18 cm −3 ) are favored in LEDs and LDs [1] to realize lower resistance and better ohm contact.…”