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Hybrid ZnO/GaN distributed Bragg reflectors grown by plasma-assisted molecular beam epitaxy

David Adolph (Institutionen för mikroteknologi och nanovetenskap, Fotonik) ; Reza R. Zamani ; Kimberly A. Dick ; Tommy Ive (Institutionen för mikroteknologi och nanovetenskap, Fotonik)
APL Materials (2166-532X). Vol. 4 (2016), 8, p. 086106.
[Artikel, refereegranskad vetenskaplig]

We demonstrate crack-free ZnO/GaN distributed Bragg reflectors (DBRs) grown by hybrid plasma-assisted molecular beam epitaxy using the same growth chamber for continuous growth of both ZnO and GaN without exposure to air. This is the first time these ZnO/GaN DBRs have been demonstrated. The Bragg reflectors consisted up to 20 periods as shown with cross-sectional transmission electron microscopy. The maximum achieved reflectance was 77% with a 32 nm wide stopband centered at 500 nm. Growth along both (0001) and (000-1) directions was investigated. Low temperature growth as well as two-step low/high-temperature deposition was carried out where the latter method improved the DBR reflectance. Samples grown along the (0001) direction yielded a better surface morphology as revealed by scanning electron microscopy and atomic force microscopy. Reciprocal space maps showed that ZnO(000-1)/GaN reflectors are relaxed whereas the ZnO(0001)/GaN DBRs are strained. The ability to n-type dope ZnO and GaN makes the ZnO(0001)/GaN DBRs interesting for various optoelectronic cavity structures.

Nyckelord: DBR, ZnO, GaN, MBE

Denna post skapades 2016-10-13. Senast ändrad 2016-10-19.
CPL Pubid: 243307


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