Growth of GaN microstructure and its applications in opto-electronics and spintronics
Ikai Lo1*
1Physics, National Sun Yat-Sen University, Kaohsiung, Taiwan
* presenting author:Ikai Lo,
GaN exhibits a stable wurtzite structure in nature, which received 2014’s Nobel laurel due to the material being a new-generation and energy-saving white light source, such as light-emitting diode (LED). The commercial white-light LEDs are mostly made of a phosphor-assisted InGaN/GaN quantum well (QW), e.g., coating by cerium-doped yttrium aluminum garnet, YAG. We have developed a technique to grow individual red-green-blue InGaN/GaN micro-disk QWs, which can produce the white light without the assistance of any phosphor for the energy sustainable lighting source. The wurtzite GaN microstructures were grown by plasma-assisted molecular beam epitaxy (MBE) and a self-assembling mechanism of GaN microstructures was established [1,2]. The luminescence intensity of the GaN micro-disk is one order of amplitude greater than that from M-plane GaN. Based on the technique, we are able to fabricate InGaN/GaN micro-disk QWs for phosphor-free white-light LED [3,4]. We also demonstrated the electrical contacts for the InGaN/GaN micro-disk by I-V characteristic measurements [5]. In addition to the growth and characterization of GaN microdisks, the current development of GaN-based nanostructure grown on ZnO substrate[6] and its applications in spintronics [7,8] will be discussed as well.
[1] Ikai Lo*, et al., “Self-assembled GaN hexagonal Micro-pyramid and micro-disk”, Appl. Phys. Lett. 94, 062105 (2009). Selected for the Cover of Appl. Phys. Lett. 2009 February 09 issue. US Patent, No. US 8,728,235 B2 (May 20, 2014)
[2] Ikai Lo*, et al., “Self-confined GaN heterophased quantum wells”, Appl. Phys. Lett. 96, 222105 (2010). US Patent, No. US 8,766,237 B2 (July 1, 2014)
[3] Yu-Chi Hsu, Ikai Lo*, et al., “InGaN/GaN single-quantum-well microdisk”, Appl. Phys. Lett 100, 242101(2012). US Patent, No. US 8,916,458 B2 (Dec. 23, 2014)
[4] Yu-Chi Hsu, Ikai Lo*, et al., “Green light emission by InGaN/GaN multiple-quantum-well microdisks”, Appl. Phys. Lett. 104, 102105 (2014), US Patent, No. US 9,147,808 B2 (Sep. 29, 2015)
[5] Ikai Lo*, et al., “Electrical contact for wurtzite GaN microdisks”, Appl. Phys. Lett. 105, 082101 (2014). US Patent, pending (2015).
[6] Shuo-Ting You, Ikai Lo,* et al., “Epitaxial growth of M-plane GaN on ZnO micro-rods by plasma-assisted molecular beam epitaxy”, AIP Advances 5, 127201 (2015).
[7] Ikai Lo*, et al., “Gate-controlled spin splitting in GaN/AlN quantum wells”, Appl. Phys. Lett. 88, 082108, (2006). 中華民國專利 : 第I 378583號 (2010)
[8] Ikai Lo*, et al. (2007), “Anomalous k-dependent spin splitting in wurtzite AlxGa1-xN/GaN heterostructures”, Physical Review B 75, 245307.

Keywords: GaN, MBE, LED, Spintronics