808nm laser diode wafer is offered by PAM-XIAMEN on N-type GaAs substrate. According to the material used in the active area, the LD wafer is mainly divided into two kinds with aluminum and without aluminum. More details please see below:
1. Laser Diode Wafer Specs
No. 1 808nm Epi Wafer for Laser Diode
No. 2 808nm Al Free LD Structure (PAMP21226-LD808)
P+ GaAsP >5E19, d=-
P- AlGaInP and undoped AlGaInP, d~-
Undoped GaInAsP QW PL: 790+/-10nm
Undoped AlGaInP and N- AlGaInP, d~1.8um
N GaAs buffer
N GaAs substrate N=(0.4~4) x 1018 d=350~625um (100)10° off <111>A.
2. About Al-containing Laser Diode Epitaxial Wafer
Since GaAs-based epitaxial wafers for laser diode have a certain light absorption for the lasing wavelength of 808nm, the electro-optical conversion efficiency of 808 nm devices is about 5%-10% lower than that of 976 nm. Generally, the efficiency of 808 nm QCW laser diode arrays is 50%. %-55%, the best level in the laboratory is about 65%. In the choice of materials, aluminum-containing materials (AlGaAs) have high electrical conductivity and thermal conductivity, and it is easy to achieve low series resistance and thermal resistance through composition gradient and doping control, and the AlGaAs-based material epitaxial growth process is mature and reliable. Therefore, the laser diode wafer containing Al is the most ideal material to achieve high electro-optical conversion efficiency at 808 nm.
However, AlGa(In)As/GaAs stack laser diode materials contain aluminum in the active area and are easily oxidized to produce high-density oxides to form deep-level defects, which are easy to form dark line defects (DLD). The formation and diffusion of DLD will cause the degradation of device performance, thereby affecting the long-term reliability of the laser.
Laser device manufactured on aluminum-containing LD semiconductor wafer are affected by optical power, driving current, and thermal effects during operation, and the cavity surfaces are easily oxidized, which will aggravate device degradation and even cause catastrophic optical damage (COD) or catastrophic optical mirror damage ( COMD), make the device invalid.
3. About Al-free Laser Diode Epi Wafer
Al-free materials are one of the ways to solve the reliability problem of high-power semiconductor lasers. Laser wafer with Al free active region refers to InGaAsP materials that closely match the GaAs lattice, and AlGaInP materials are also included in actual work. The laser wavelength range that can be achieved by aluminum-free laser diode structure grown on a GaAs substrate is 650~1060 nm, covering all wavelengths of AIGa(In)As materials.
Compared with AlGaAs/GaAs wafer, the laser diode wafer without Al composition have the following main advantages:
- InAlGaAs quantum well 808nm laser diode wafers have a higher COMD power density than aluminum-containing materials. The Al in the active area is easy to oxidize and produce dark line defects, which reduces the power density when COMD occurs, and it is easier to produce COMD, thereby limiting the power and life of the laser.
- At the same time, compared with aluminum-containing quantum wells, aluminum-free quantum wells have lower resistance and higher thermal conductivity, so there is low recombination rate and low risen temperature on the surface, and the cavity surface degradation rate is slow. It has an inhibitory effect on the climbing of dark line defects, and the internal degradation rate of the material is slow.
The high-power semiconductor laser and its pumped solid-state laser, which are fabricated on laser diode wafer have broad application prospects in advanced manufacturing, medical beauty, aerospace, and laser display. In these applications, miniaturization and light weight of semiconductor lasers are often required, and improving the electro-optical conversion efficiency of semiconductor lasers is the most effective technical way to reduce the energy consumption, volume and weight of the entire laser system.