The a-axis lattice parameter of Bi2Se3 is almost identical to the lattice periodicity of the InP (1 1 1) surface. We consequently obtain remarkably smooth Bi2Se3 (0 0 0 1) layers in hot-wall-epitaxy growth on InP (1 1 1)B substrates. The lattice-matched periodicity is preserved in the [1 1 0] and [ ] directions of the (0 0 1) surface. The Bi2Se3 layers grown on InP (0 0 1) substrates exhibit 12-fold in-plane symmetry as the [ ] direction of Bi2Se3 is aligned to either of the two directions. When the (1 1 1)-oriented InP substrates are inclined, the Bi2Se3 (0 0 0 1) layers are found to develop steps having a height of ~50 nm. The tilting of the Bi2Se3 [0 0 0 1] axis with respect to the growth surface is responsible for the creation of the steps. Epitaxial growth is thus evidenced to take place rather than van der Waals growth. We point out its implications on the surface states of topological insulators.
An epitaxially grown GaInAsP/InP double-hetero laser diode (LD) has been demonstrated on a wafer-bonded InP/Si substrate for the first time. The as-grown structure was optically active and exhibited a photoluminescence intensity comparable to that grown on an InP wafer as a reference. Electrodes were formed on both the p-side contact layer and the n-Si underside to fabricate Fabry–Perot LD chips. During these processes, the InP layer remained bonded to the underlying Si substrate. Electrically pumped lasing emission was observed at room temperature under a pulse regime. These results indicate the potential for the high-density integration of InP-based LDs as a light source for optical interconnections.
Helium implantation-induced layer splitting of InP in combination with direct wafer bonding was utilized to achieve low temperature layer transfer of InP onto Si(1 0 0) substrates. InP(1 0 0) wafers with 4 inch diameter were implanted by 100 keV helium ions with a dose of 5 × 1016 cm−2. Then the as-implanted wafers were coated with a spin-on glass (SOG) oxide having a thickness of 150 nm. The SOG coated InP wafers were subsequently bonded to thermally oxidized Si(1 0 0) handle wafers and the bonded wafer pairs were annealed at 200 °C for 20 h to achieve InP layer transfer onto Si(1 0 0) wafers, enabling monolithic integration of InP with Si. Cross-sectional transmission electron microscope images of the transferred InP layers revealed that the layers were about 650 nm thick, which consisted of a heavily damaged InP layer about 300 nm thick directly at the surface and a remaining 350 nm thick layer with considerably less damage.
Current-injected light emission was confirmed for metal organic vapor phase epitaxy (MOVPE) grown (Ga)InAs/InP quantum dots (QDs) on directly bonded InP/Si substrate. The InP/Si substrate was prepared by directly bonding of InP thin film and a Si substrate using a wet-etching and annealing process. A p–i–n LED structure including Stranski–Krastanov (Ga)InAs/InP QDs was grown by MOVPE on an InP/Si substrate. No debonding between Si substrate and InP layer was observed, even after MOVPE growth and operation of the device under continuous wave conditions at RT. The photoluminescence, current/voltage, and electroluminescence characteristics of the device grown on the InP/Si substrate were compared with reference grown on an InP substrate.