Study on P-AlGaAs/Al/Au Ohmic Contact Characteristics for Improving Optoelectronic Response of Infrared Light-Emitting Device

Hyung-Joo Lee; Jae-Sam Shim; Jin-Young Park; Lee-Ku Kwac; Chang-Ho Seo

doi:10.3390/mi14051053

Study on P-AlGaAs/Al/Au Ohmic Contact Characteristics for Improving Optoelectronic Response of Infrared Light-Emitting Device

Micromachines (Basel). 2023 May 16;14(5):1053. doi: 10.3390/mi14051053.

Authors

Hyung-Joo Lee¹, Jae-Sam Shim², Jin-Young Park², Lee-Ku Kwac³, Chang-Ho Seo⁴

Affiliations

¹ CF Technical Division, AUK Corporation, Iksan 54630, Republic of Korea.
² Korea Photonic Technology Institute (KOPTI), Gwangju 61007, Republic of Korea.
³ Graduate School of Carbon Convergence Engineering, Jeonju University, Jeonju 55069, Republic of Korea.
⁴ Department of Convergence Science, Kongju National University, Chungnam 32588, Republic of Korea.

Abstract

The Al/Au alloy was investigated to improve the ohmic characteristic and light efficiency of reflective infrared light-emitting diodes (IR-LEDs). The Al/Au alloy, which was fabricated by combining 10% aluminum and 90% gold, led to considerably improved conductivity on the top layer of p-AlGaAs of the reflective IR-LEDs. In the wafer bond process required for fabricating the reflective IR-LED, the Al/Au alloy, which has filled the hole patterns in Si₃N₄ film, was used for improving the reflectivity of the Ag reflector and was bonded directly to the top layer of p-AlGaAs on the epitaxial wafer. Based on current-voltage measurements, it was found that the Al/Au alloyed material has a distinct ohmic characteristic pertaining to the p-AlGaAs layer compared with those of the Au/Be alloy material. Therefore, the Al/Au alloy may constitute one of the favored approaches for overcoming the insulative reflective structures of reflective IR-LEDs. For a current density of 200 mA, a lower forward voltage (1.56 V) was observed from the wafer bond IR-LED chip made with the Al/Au alloy; this voltage was remarkably lower in value than that of the conventional chip made with the Au/Be metal (2.29 V). A higher output power (182 mW) was observed from the reflective IR-LEDs made with the Al/Au alloy, thus displaying an increase of 64% compared with those made with the Au/Be alloy (111 mW).

Keywords: Al/Au alloy; light-emitting diode; ohmic contact; p-AlGaAs; reflective structure.

Grants and funding

This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education [grant numbers 2016R1A6A1A03012069 and 2018R1D1A1B07050752]. It also was supported by the Institute of Information and Communications Technology Planning and Evaluation (IITP) Grant by the Korean Government through MSIT (Robust AI and Distributed Attack Detection for Edge AI Security) under Grant 2021-0-00511.