Monolithic Integration of GaAs/InGaAs Lasers on Virtual Ge Substrates via Aspect-Ratio Trapping

Abstract

GaAs/InGaAs quantum-well lasers have been demonstrated by metallorganic chemical vapor deposition on virtual Ge substrates on Si via aspect-ratio trapping ͑ART͒ and epitaxial lateral overgrowth ͑ELO͒. Laser-structure growth is achieved in two steps: The first step is growing uncoalesced defect-free Ge stripes on a SiO 2 trench-patterned silicon substrate via ART, whereby the misfit defects originating from the Ge/Si interface are trapped by laterally confining sidewalls. Defects arising from above the SiO 2 film are reduced by using an optimized ELO process followed by chemical mechanical polishing to provide a planar Ge surface. The second step is overgrowing a GaAs/InGaAs laser structure on the virtual Ge substrate. A number of GaAs/Ge integration issues, including Ge autodoping and antiphase domain defects in GaAs, have been overcome. Despite unoptimized laser structures with high series resistance and large threshold current densities, pulsed room-temperature lasing at a wavelength of 980 nm has been demonstrated using a combination of ART and ELO. This technique is very promising for the achievement of reliable GaAs-based optoelectronic devices on Si.

Quantum dot lasers for silicon photonics [Invited]

“…Other groups have reported good performance of quantum well lasers epitaxially grown on silicon substrates through sufficient reductions in dislocation density [31][32][33]. However, the reliability of such lasers remains a concern, particularly for GaAs-based lasers, which are susceptible to recombinationenhanced defect reactions [5,34].…”

Thin Ge buffer layer on silicon for integration of III-V on silicon

“…Various techniques, including growing thick III-V buffer layers with dislocation filter layers (DFLs) have been used to improve the material quality of the III-V photonic devices on Si [13][14][15]. Implementing quantum confined materials, such as quantum wells and quantum dots (QDs) [16][17][18][19], has allowed for further improvements in the devices quality and realization of the first functional lasers [20]. Recently, a long lifetime electrically-pumped continuous-wave III-V quantum dot laser monolithically grown on silicon has been successfully demonstrated by Chen et al [7].…”

Heteroepitaxial Growth of GaAs/Ge Buffer Layer on Si for Metamorphic InGaAs Lasers

“…However, for high-performance (high-speed, high-reliability) LDs, further improvements in the buffer layer using dislocations filters (e.g. strained layer superlattices [27], [31]- [33] or aspect ratio trapping [5], [34]- [36]) are necessary.…”

“…(LDs) on Si substrate by using Ge buffer layers with InAs quantum dots (QDs) [3], [5]- [7]. These LDs exhibited high output power with a relatively long cavity around 1 mm [3], [7], which is suitable for use in conjunction with modulators.…”