Research on Si-induced Quantum Well Intermixing Based on Cyclic Annealing（Invited）

Yuxiao WANG; Lingni ZHU; Li ZHONG; Qiong QI; Wei LI; Suping LIU; Xiaoyu MA

doi:10.3788/gzxb20225102.0251210

Abstract

Catastrophic Optical Mirror Degradation(COMD) is one of the main factors that restrict the output power and reliability of semiconductor lasers. To achieve high power and high reliability and avoid COMD at the same time, Non-absorbing Window (NAW) is often applied to semiconductor laser preparation process, which contains secondary epitaxial growth technology and Quantum Well Intermixing (QWI). For the high cost and high difficulty of secondary epitaxial growth technology, QWI is more widely used. The common methods of QWI include Rapid Thermal Annealing (RTA), Ion Implantation Induced Disordering (IIID), Laser Induced Disordering(LID), Plasma Enhancement Induced Disordering (PID), Impurity Free Vacancy Disordering (IFVD) ,Impurities Induced Disordering (IID), etc. RTA is easy to achieve, which only needs high temperature annealing, but the repeatability and reliability is low. On the contrary, IIID, LID and PID do well in repeatability and reliability, expensive equipment is needed, however. Besides, IFVD is often conducted in relatively higher temperature. Compared to such methods above, IID technology causes impurity atoms such as Si and Zn diffuse from surface of epitaxial layer into active layer with lower temperature and high repeatability, leading to inter-diffusion of group Ⅲ atoms between quantum well and barrier, which widen the band gap of quantum well.The mechanism of Si-induced QWI has been controversial, and the Si

_{G a}^{+}

-V

_{G a}^{-}

pair model is widely used. In the Si

_{G a}^{+}

-V

_{G a}^{-}

pair model, the diffusion coefficient of isolated Si is small. Si occupies gallium vacancies (V_Ga) to form Si

_{G a}^{+}

. The adjacent Si

_{G a}^{+}

and V_Ga forms Si

_{G a}^{+}

-V

_{G a}^{-}

neutral pair, diffusing by exchanging with surrounding V_Ga and Si

_{G a}^{+}

.In this paper, Si-induced QWI under different conditions was explored and applied to the fabrication of 975 nm semiconductor laser devices, using the cyclic annealing method . When the annealing test is carried out under temperature 830 ℃ at a duration of 10 min in 3 cycles , the maximum wavelength blue shift is 59 nm. NAW was fabricated under 800 ℃ at a duration of 10 min in 5 cycles and 830 ℃ at a duration of 10 min in 3 cycles, separately. The results show that threshold current and slope efficiency of the semiconductor lasers with NAW increases compared with ordinary devices. When the operating current is greater than 10 A, the slope efficiency of the devices decrease, and the Power-Current curves indicates a tendency towards saturation. The performance of the devices prepared under 800 ℃ at a duration of 10 min in 5 cycles is relatively better. Ordinary devices fail when the operating current reaches 15 A. Devices with NAW can still work normally after the current is greater than 20 A, and the COMD threshold is increased by more than 33.0%.