Fabrication of 1.55 μm VCSELs using metallic bonding on Si substrates

Using Au-based multi-layered metals as the wafer bonding medium, long-wavelength GaInAsP/InP VCSELs were fabricated on Si substrates. High contrast Al-oxide/Si (Δn∼1.6) were employed as the upper and lower DBRs such that the need to grow thick epitaxial DBRs is eliminated. The bonding process can be performed at a low temperature around 320°C and it does not require any special treatment and alignment on the bonding wafers. The bonding interface was formed outside the VCSEL cavity, which reduced the impact on the active region of the device brought by the bonding process. Laser emission at 1.545 μm was measured under pulsed operations near room temperature. The low-temperature metallic bonding process demonstrates a great potential in device fabrication.