GaP/Si Heterojunction with Ohmic Conduction Fabricated by Wafer Fusion Technique

In this letter, we report the fabrication of a GaP/Si heterojunction with ohmic conduction by a wafer fusion technique. After a hydrophilic pretreatment, GaP and Si wafers were brought in contact and annealed at 500°C in a flowing forming gas for 30 min. The electrical properties of n-GaP/n + -Si and p + -GaP/n + -Si junctions fabricated by this procedure were investigated. The n-GaP/n + -Si junction exhibited potential barriers for both directions, indicating Fermi-level pinning due to high-density interface states at the fused interface. For the p + -GaP/n + -Si junction, ohmic conduction (10–20 Ω·cm 2 ) was observed. This may be due to carrier transport by a tunneling process. The wafer fusion technique of GaP/Si is applicable to optoelectronic integrated circuits (OEICs) and high-efficiency tandem-type solar cells.