Structural Design And Fabrication Of808-nm Vertical-Cavity Surface-Emitting Laser

Vertical-cavity surface-emitting lasers（VCSEL） shows many advantages toedge-emitting semiconductor laser such as low threshold current, not subject to CODand easy fabrication in two-dimensional arrays.808-nm semiconductor lasers are usedto pump solid state lasers. However, we find very few reports on808-nm VCSEL afteran extensive literature search, because it is only actively studied in recent years. Thispaper focuses on the design of quantum well, distributed Bragg reflector （DBR） andoverall structure, and the fabrication for808-nm VCSEL device. The mainachievements are as follows:（1）Vertical-cavity surface-emitting lasers emitting at808nm with unstrainedGaAs/Al_0.3Ga_0.7As, tensilely strained GaAs_xP_1-x/Al_0.3Ga_0.7As and compressivelystrained In_1-x-yGax_Al_yAs/Al_0.3Ga_0.7As quantum wells have been investigated. Based ona comprehensive model, the composition and the width of these quantum wells aredetermined. The numerical simulation shows that the emission wavelength is near800nm at room temperature for GaAs well with width of4nm, GaAs_0.87P_0.13well withwidth of13nm and In_0.14Ga_0.74Al₍0.12As well with width of6nm.（2） The high refractive index Al_0.2Ga_0.8As and the low refractive indexAl0.9Ga0.1As for the DBR of808-nm VCSEL are determined. Using transmissionmatrix method, the spectral reflectance of DBR is plotted. The designed Al_0.9Ga_0.1As/Al_0.2Ga_0.8As DBR is gradient, and the thickness of the gradient layer is20nm. In addition, The P-DBR has23pairs with the reflectance of99.57%, and theN-DBR has39.5pairs with the reflectance of99.94%.（3） The material gain, threshold current and output power of the three designedquantum-well VCSEL are studied and compared. The results indicate thatIn_0.14Ga_0.74Al₍0.12As is the most appropriate candidate for the quantum well of808-nmVCSEL. Then the quantum well of In_0.14Ga_0.74A_l0.12As, the Al_0.9Ga_0.1As/Al_0.2Ga_0.8AsDBR of22pairs and the overall structure of VCSEL are grown by MOCVD. Themeasurements show that the central wavelengths of the photoluminescence spectrumfor quantum well, the reflection spectrum for DBR, and the cavity mode for VCSELare basically consistent with the theoretical results.（4） Adopting the top emission technology, the single emitter and array of808-nmVCSEL devices were processed. The maximum output power of the single emitter is43mW when the aperture of diameter is150μm. The maximum output power of the2×2arrays is115mW. The spectral center wavelength of the single emitter and arraydevice is around808nm, which is exactly the result we want.