Abstract
In this study, high internal-quantum-efficiency (IQE) AlGaN multiple quantum wells (MQWs) were successfully demonstrated on low-defect-density AlN templates with nano-patterned sapphire substrates. These templates consisted of AlN structures with 0∼30 periods superlattices (SLs) by alternating high (100) and low (25) V/III ratios under a low growth temperature (1130 °C). Compared to conventional high crystal-quality AlN epilayers achieved at temperatures ≥1300 °C, lower thermal budget can reduce the production cost and wafer warpage. Via optimization of the SL period, the AlN crystallinity was systematically improved. Strong dependence of SL period number on the X-ray full-width-at-half-maximum (FWHM) of the AlN epilayer was observed. The AlN template with 20-period SLs exhibited the lowest FWHM values for (0002) and (10ī2), namely 331 and 652 arcsec, respectively, as well as an ultra-low etching pit density of 1 × 105 cm−2. The relative IQE of 280 nm AlGaN MQWs exhibited a dramatically increase from 22.8% to 85% when the inserted SL increased from 0 to 20 periods. It has hardly ever been reported for the AlGaN MQW sample. The results indicate that the engineered AlN templates have high potential applications in deep ultraviolet light emitters.
Highlights
Deep-ultraviolet light-emitting-diodes (DUV-LEDs) have attracted attention because of their wide range of potential applications in food disinfection and air/water purification, as well as in the sensing of gases (e.g., SO2 and NOx)[1]
At growth step-4 (Fig. 2(d)), the epilayer coalesced, and some holes were observed on the patterned regions. These results indicated that the growth evolution of the AlN epilayer is dominated by epitaxial lateral overgrowth (ELOG)
The low-defect-density AlN templates were successfully fabricated under a low growth temperature (1130 °C) to achieve high-IQE multiple quantum wells (MQWs)
Summary
Deep-ultraviolet light-emitting-diodes (DUV-LEDs) have attracted attention because of their wide range of potential applications in food disinfection and air/water purification, as well as in the sensing of gases (e.g., SO2 and NOx)[1]. Several researchers have proposed methods to improve the crystallinity of AlN, including the enhancement of surface migration for Al adatoms[4], use of AlN grown at high temperatures (≥1300 °C)[5], AlN superlattices (SLs) with the alternation of low and high temperatures as a buffer structure[6], the use of an AlGaN/AlN SL buffer structure[7], and an AlN epilayer grown on a nano-patterned sapphire substrate (NPSS)[8] Besides these methods, Shatalov et al have reported enhancement in the IQE of AlGaN-based MQWs by the use of an AlN template with a low dislocation density[9]. The result suggests that the high-IQE AlGaN MQW structure can be achieved using an engineered low-defect-density AlN template
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
