Microstructure of GaAs/GaN interfaces produced by direct wafer fusion

Abstract

Results of a Transmission Electron

Interface structure and adhesion of wafer-bonded GaN/GaN and GaN/AlGaN semiconductors

“…2 presents the interface of a wafer-bonded GaN/GaN and Al 0.25 GaN 0.75 /GaN samples prepared at 1000°C for 1 h. Both SEM and TEM images of GaAs͑111͒/ GaAs͑111͒ and a SEM image of GaN/GaN indicate uniform and well-bonded interfaces. The amorphous nanoinclusions observed in GaAs͑001͒/GaAs͑001͒, GaAs͑001͒/InP͑001͒, and GaAs͑001͒/GaN bonded interfaces 3,8 were not seen in the GaAs͑111͒/GaAs͑111͒ system. Even though the TEM interface image of GaN/GaN is not available in this study, it is reasonable to expect that the GaN/GaN interface would also show a similar uniform boundary.…”

“…͑1͒ The wafer-bonded interface is not composed of 100% well-fused crystalline bonds. 3,4,8,9 The interfacial imperfections introduce a large number of dangling bonds and a local amorphous region of about 20%-30%, 8 forming many local weakly bonded interface areas, which can certainly reduce the overall interface adhesion. It is worth noting that the prebonding semiconductor interfaces in Ref.…”

“…[1][2][3][4] Furthermore, the large band discontinuity creates an Al x Ga 1Ϫx N/GaN heterointerface that can confine an unusually high density of electrons in a two-dimensional electron gas. A modulation-doped field-effect transistor based on the Al x Ga 1Ϫx N/GaN heterostructures has shown encouraging high-frequency, high-power, and high-temperature performance.…”

“…5 One of the major challenges in group III nitride semiconductors is the heterogeneous integration of free standing GaN-based devices with dissimilar substrates. [3][4][5][6] Direct wafer bonding has been reported to be an ideal approach to integrate mismatched materials and has been used to fabricate a number of advanced microelectronic or photonic devices. 3,4,6,7 Wafer bonding of GaN and other related semiconductors has been reported by a few research groups, such as GaN/GaAs, 3,4 GaN/InP, 6 and GaN/GaN.…”

“…[3][4][5][6] Direct wafer bonding has been reported to be an ideal approach to integrate mismatched materials and has been used to fabricate a number of advanced microelectronic or photonic devices. 3,4,6,7 Wafer bonding of GaN and other related semiconductors has been reported by a few research groups, such as GaN/GaAs, 3,4 GaN/InP, 6 and GaN/GaN. 7 However, to date, only a little effort has been focused on understanding the correlations among bonding process, wafer surface or interface microstructures, and interface adhesion.…”