Study on the p-type ohmic contact in GaAs-based laser diode

• Published in: Materials science in semiconductor processing 2021-03, Vol.124, p.105622, Article 105622
• Main Authors: Lin, Tao, Xie, Jia-nan, Ning, Shao-huan, Li, Qing-min, Li, Bo
• Format: Article
• Language: English
• Subjects: CTLM; GaAs; Ohmic contact; Specific contact resistivity
• ISSN: 1369-8001; 1873-4081
• DOI: 10.1016/j.mssp.2020.105622

In this paper, the p-GaAs ohmic contact, which is important to improve the conversion efficiency and long-term reliability of high-power optoelectronic devices, was studied. The p-GaAs layer was grown by metal-organic chemical vapor deposition (MOCVD) with a hole concentration of 1.2×1020cm-3, and the metal electrode was fabricated by E-beam evaporation technology based on Ti/Pt/Au metal system. The CTLM tests showed that the p-GaAs contacts were both typical ohmic contact before and after annealing, and the smallest specific contact resistivity of 4.8×10-6Ω·cm2 was obtained after annealing, which mainly due to the direct tunneling effect on the highly doped p-GaAs surface and the formed non-alloy ohmic contact. SEM and EDX analysis showed that the annealing processes used in the n-GaAs metal alloy for laser diode had a little influence on the surface morphology and inter-diffusion of As, Pt, Au elements, while it enhanced the inter-diffusion of Ga and Ti in the contact. •The p-GaAs samples showed typical ohmic contact before and after annealing.•The smallest specific contact resistance is 4.8 × 10-6 Ω cm2.•We found the annealing processes enhanced the interdiffusion of Ga and Ti in the contact.