A new type of multiple micro-cavity (MMC) laser was proposed and fabricated.
A GaInAsP/InP semiconductor collimating GRIN lens was proposed and fabricated for optical coupling improvement of SLA and LD to single mode fiber.

Results obtained in this research are as follows.

(1) A new type of multiple micro-cavity (MMC) laser with etched mirrors was proposed, and it was found that it is possible to operate on sub-mA current.

(2) Nearly vertical shape etched mirrors by using wet chemical etching was obtained

(3) Threshold current density of 178A/cm² was obtained at room temperature under pulsed condition in MMC lasers.

(4) CW operation was obtained at room temperature in MMC lasers.

(5) A semiconductor collimating GRIN lens for vertical output beam divergence improvement of SLA and LD was fabricated, and integration with TTW-SLA was demonstrated.

GaInAsP/InP strained-quantum-film, -wire, and -box lasers have been studied both theoretically and experimentally. Temperature dependences of GaInAsP/InP compressively-strained single-quantum-well lasers with quantum-wire (Q-Wire) size active region were measured and compared with those of quantum-film (Q-Film) lasers. Better lasing properties of the Q-Wire laser over Q-Film lasers were confirmed at a temperture below 193K. A GaInAsP/InP compressively-strained quantum-box laser assisted with a thin quantum-film active layer was operated at 77K under CW condition.

Results obtained in this research are as follows.

(1) Temperature dependences of GaInAsP/InP compressively-strained single-quantum-well lasers with quantum-wire (Q-Wire) size active region were measured and compared with those of quantum-film lasers. Lower threshold current as well as higher differential quantum effciency operation of Q-Wire laser than those of Q-Film laser at a temperture below 193K were obtained. Threthold current density of Q-Wire laser was 43A/cm2 which was almost a half that of Q-Film laser being 85A/cm².

(2) A GaInAsP/InP compressively-strained(CS,+1%) quantum-box laser assisted with a thin quantum-film active layer(CS,+1%,5nm) was operated at 77K under CW condition.The threshold current density was 603A/cm². The fabricated quantum-box size is 22nm diameter and 10nm thick with a period of 70nm.

(3) By combining electron beam lithography and Cl₂-ECR dry etching with negative acceleration voltage, 10-40nm wide GaInAsP/InP multi-quantum-wire structures were fabricated. Moreover, low damage feature of this fabrication process was confirmed by PL observation. An introduction of a surface cleaning process with H₂ gas just after Cl₂-ECR dry etching was found to be effective for further reduction of damage.

Study of nanometer structure fabrication technique is important for the realization of quantum effect devices such as quantum-wire or -box devices and ballistic electron devices based on wave characteristics of electrons.

Results obtained through this year are as follows.

(2) Heterointerface of GaInAs/InP grown by OMVPE were observed by Atomic Force Microscope (AFM). Atomically flat regions was obtained on InP surface by optimized annealing prosess. To realize the atomically flat heterointerface, we investigated the relation between growth conditions and growth modes such as step-flow and/or two-dimensional nucleation for InP surface.

(3) Anodization process of InP has been investigated with aiming at a novel fabrication technology of quality quantum-wire and quantum-box structures. As the result, a high density (space filling factor of 50%), uniformly shaped (triangle) and sized (40nm) vertical pillar structure was obtained on (111)A oriented InP substrate with a SiO₂ mask by adopting an EBX direct patterning followed by the anodization with HCl acid. Very small physical damage by anodization process was established from observing strong PL intensity from 40nm size-ordered triangle pillers.