ABSTRACT
The AlGalnN-based laser chip structure is shown schematically in Fig. 1(a). The layer structures were grown by metal-organic chemical vapor deposition (MOCVD) on the ELO-GaN substrate having a periodic low dislocation-density region of approximately 106 cm'2, parallel to the [1-100] direction of the GaN layer. The thickness of the basal ELO-GaN layer was restricted to less than 5 pm in order to prevent serious wafer bending, which degrades the uniformity of stripe emitter width on the wafer. As our concept for realizing SHP-LDs is based only on the integration of high-performance multi-stripe emitters into one laser ship,
Fig. L Schematic diagram of (a) AlGalnN-based laser chip structure with 4 stripe emitters, and (b) fabricated SHP-LD array
the vertical wave-guide structures and stripe width employed are almost identical to those reported recently [8 ]. A 1.3 pm-thick n-Alo.08Gao.92N cladding layer was grown over the ELO-GaN layer, followed by a 0.1 pm-thick η-GaN guiding layer, a Gao.98lno.02N/Gao.90Ino.10N/Gao.98lno.02N multiple-quantum-well active layer, a 30 nm-thick
InGaN interlayer, a 10 nm-thick p-Alo.10Gao.84N layer to prevent electron overflow, a 0.1 pm-thick p-GaN guiding layer, a 0.5 pm-thick modulation-doped p-Alo.15Gao.85N/GaN superlattice cladding layer, and a 0.1 pm-thick p-GaN contact layer. The 1.5 pm-wide ridge stripes were formed on the laterally overgrown wing regions between the seed and coalescence regions. The p-type electrode (Pd/Pt/Au) and the n-type electrode (Ti/Pt/Au) were evaporated onto the p-and n-GaN contact layer, respectively. The front facet and the rear facet were coated with a 5% anti-reflectant film and a 95% high-refrectant film.
