Y. Qian

Long wavelength (1.3 μm) vertical-cavity surface-emitting lasers with a wafer-bonded mirror and an oxygen-implanted confinement region

We proposed and demonstrated a novel design for long wavelength (1.3 μm) vertical-cavity surface-emitting lasers (VCSELs). In this design, oxygen-implanted current-confinement regions were formed in a GaAs/AlGaAs Bragg reflector which is the bottom mirror wafer bonded to an AlGaInAs/InP cavity consisting of nine strain-compensated quantum wells. Room- temperature continuous-wave (cw) operation of 1.3 μm-VCSELs with a record low cw threshold current density of 1.57 kA/cm2 and a record low cw threshold current of 1 mA have been realized.

1.3-μm Vertical-cavity surface-emitting lasers with double-bonded GaAs-AlAs Bragg mirrors

We demonstrate, for the first time, double-bonded AlGaInAs strain-compensated quantum-well 1.3-/spl mu/m vertical-cavity surface-emitting lasers (VCSELs). GaAs-AlAs Bragg mirrors were wafer-bonded on both sides of a cavity containing the AlGaInAs strain-compensated multiple-quantum-well active layers sandwiched by two InP layers. The lasers have operated under pulsed conditions at room temperature. A record low pulsed threshold current density of 4.2 kA/cm/sup 2/ and a highest maximum light output power greater than 4.6 mW have been achieved. The maximum threshold current characteristic temperature T/sub 0/ of 132 K is the best for any long wavelength VCSELs. The laser operated in a single-longitudinal mode, with a side-mode suppression ratio of more than 40 dB, which is the best results for 1.3-/spl mu/m VCSELs.

Low-threshold proton-implanted 1.3-μm vertical-cavity top-surface-emitting lasers with dielectric and wafer-bonded GaAs-AlAs Bragg mirrors

We demonstrate a new structure for long-wavelength (1.3-/spl mu/m) vertical-cavity top-surface-emitting lasers using proton implantation for current confinement. Wafer bonded GaAs-AlAs Bragg mirrors and dielectric mirrors are used for bottom and top mirrors, respectively. The gain medium of the lasers consists of nine strain-compensated AlGaInAs quantum wells. A record low room temperature pulsed threshold current density of 1.13 kA/cm/sup 2/ has been achieved for 15-/spl mu/m diameter devices with a threshold current of 2 mA. The side-mode-suppression-ratio is greater than 35 dB.

Wafer bonding technology and its optoelectronic applications

This paper describes the wafer bonding technology and its applications to optoelectronic devices and circuits. It shows that the wafer bonding technology can create new device structures with unique characteristics and can form integrated optoelectronic circuits containing optical, electronic and micro-mechanical devices.

Wafer bonding and its application on compliant universal (CU) substrates

We have recently found a novel and significant application for the wafer bonding technology. We demonstrated that by bonding an ultra thin layer of semiconductor to a bulk crystal with a rotational angle along their surface normal, this new structure can achieve interesting behaviors as a compliant substrate. When heteroepitaxial layers are grown on such twist-bonded substrates, the bonded thin layer is plastically deformed to relax the strain before threading dislocations are nucleated in the heteroepitaxial layer. This is a new and energetically more favorable way for lattice strain relaxation and is unique to the twist-bonded structure. We found that this concept can be applied to many semiconductors such as GaAs and Si to form compliant substrates where heteroepitaxy of exceedingly large lattice mismatch (e.g. 15%) can be grown without defects. This implies that twist-bonded compliant substrates may, to a large extent, function as a universal substrate for growth of high quality materials of nearly any lattice constant.

Wafer bonding technology and its applications in optoelectronic devices

The new optoelectronic integrated technology--wafer bonding is described. The results of wafer bonding and applications in several new types of optoelectronic devices are presented.

Dosage effects on oxygen implanted single-bonded 1.3 /spl mu/m vertical-cavity surface-emitting lasers

1.3 /spl mu/m vertical-cavity surface-emitting lasers (VCSELs) will have important applications in local access optical networks and high-speed data links. In our earlier paper, we reported low CW threshold current 1.3 /spl mu/m VCSELs which contain InGaAlAs strain-compensated quantum wells, bonded GaAs/AlGaAs Bragg mirrors, and oxygen implanted current confinement regions. It is believed that oxygen implantation is the key for low threshold current because oxygen atoms have less lateral and vertical straggling than hydrogen atoms and the implanted region can preserve its high resistivity after high temperature wafer-bonding. In this paper we report our studies of the oxygen dosage effects on 1.3 /spl mu/m VCSELs. We have measured the threshold current, slope efficiency, and series resistance for VCSELs with two different oxygen doses but otherwise the same structure.

High performance 1.3 /spl mu/m vertical-cavity surface-emitting lasers with oxygen-implanted confinement regions and wafer-bonded mirrors

We show schematically the oxygen-implanted VCSELs. The devices consist of an oxygen implanted p-GaAs-AlGaAs (28 pairs) mirror, AlGaInAs-InP strain-compensated multiple quantum well (SC-MQW) cavity layers, and a top ZnSe/MgF (6 pairs) dielectric mirror.

Hydrogen-implanted 1.3 /spl mu/m vertical-cavity surface-emitting lasers with dielectric and wafer-boned GaAs/AIAs mirrors

A 1.3 {micro}m wavelength vertical-cavity surface-emitting laser (VCSEL) containing proton implanted isolation regions and a dielectric top mirror and a wafer-bonded GaAs/AlAs bottom mirror was fabricated. A room temperature pulsed threshold current density of 1.13 kA/cm{sup 2} and a threshold current of 2 mA have been demonstrated.

Wafer-bonded AlGaInAs 1.3-um vertical-cavity surface-emitting lasers

Wafer-bonded AlAs/GaAs mirrors and AlGaInAs strain- compensated multiple quantum well active layers have been applied into 1.3 micrometer vertical-cavity surface-emitting lasers (VCSELs). Double-bonded 1.3 micrometer VCSELs have operated at room temperature pulsed conditions with a high output power of 4.6 mW, a high characteristic temperature of 132 K, and a large side-mode suppression-ratio of 42 dB. A novel more practical approach for 1.3 micrometer VCSELs have been proposed and demonstrated a very low room temperature pulsed threshold current density of 1.13 kA/cm2 and a very low threshold current of 2 mA. Further improvement focusing on practical approaches for long wavelength VCSELs is underway.