Strain dependence on polarization properties of AlGaN and AlGaN-based ultraviolet lasers grown on AlN substrates

Since the band ordering in AlGaN has a profound effect on the performance of UVC light emitting diodes (LEDs) and even determines the feasibility of surface emitting lasers, the polarization properties of emitted light from c-oriented AlGaN and AlGaN-based laser structures were studied over the whole composition range, as well as various strain states, quantum confinements, and carrier densities. A quantitative relationship between the theoretical valence band separation, determined using k•p theory, and the experimentally measured degree of polarization is presented. Next to composition, strain was found to have the largest influence on the degree of polarization while all other factors were practically insignificant. The lowest crossover point from the transverse electric to transverse magnetic polarized emission of 245 nm was found for structures pseudomorphically grown on AlN substrates. This finding has significant implications toward the efficiency and feasibility of surface emitting devices below this wavelength.

[1]  Jonathan J. Wierer,et al.  Effect of thickness and carrier density on the optical polarization of Al0.44Ga0.56N/Al0.55Ga0.45N quantum well layers , 2014 .

[2]  James Tweedie,et al.  Surface preparation and homoepitaxial deposition of AlN on (0001)-oriented AlN substrates by metalorganic chemical vapor deposition , 2010 .

[3]  E. O’Reilly,et al.  Band gap bowing and optical polarization switching in Al 1−x Ga x N alloys , 2015 .

[4]  Wei Guo,et al.  Lasing and Longitudinal Cavity Modes in Photo-Pumped Deep Ultraviolet AlGaN Heterostructures , 2013 .

[5]  Z. Sitar,et al.  Exciton transitions and oxygen as a donor in m-plane AlN homoepitaxial films , 2014 .

[6]  Michael Kneissl,et al.  Effect of strain and barrier composition on the polarization of light emission from AlGaN/AlN quantum wells , 2012 .

[7]  Nelson Tansu,et al.  Effect of crystal-field split-off hole and heavy-hole bands crossover on gain characteristics of high Al-content AlGaN quantum well lasers , 2010 .

[8]  Ashok K. Saxena,et al.  The conduction band structure and deep levels in Ga1-xAlxAs alloys from a high-pressure experiment , 1980 .

[9]  K. Hiramatsu,et al.  Correlation between in-plane strain and optical polarization of Si-doped AlGaN epitaxial layers as a function of Al content and Si concentration , 2012 .

[10]  Yuh-Shiuan Liu,et al.  Deep-ultraviolet lasing at 243 nm from photo-pumped AlGaN/AlN heterostructure on AlN substrate , 2013 .

[11]  K. Forghani,et al.  Composition dependent valence band order in c-oriented wurtzite AlGaN layers , 2014 .

[12]  Wei Guo,et al.  Stimulated emission and optical gain in AlGaN heterostructures grown on bulk AlN substrates , 2014 .

[13]  Yoichi Kawakami,et al.  Optical anisotropy in [0001]-oriented AlxGa1-xN/AlN quantum wells (x>0.69) , 2009 .

[14]  Hongen Shen,et al.  Pseudomorphically Grown Ultraviolet C Photopumped Lasers on Bulk AlN Substrates , 2011 .

[15]  H. Kawanishi,et al.  Experimental energy difference between heavy- or light-hole valence band and crystal-field split-off-hole valence band in AlxGa1−xN , 2006 .

[16]  Michael Wraback,et al.  High Output Power from 260 nm Pseudomorphic Ultraviolet Light-Emitting Diodes with Improved Thermal Performance , 2011 .

[17]  M. Weyers,et al.  Impact of light polarization on photoluminescence intensity and quantum efficiency in AlGaN and AlInGaN layers , 2012 .

[18]  Toru Kinoshita,et al.  Light extraction enhancement of 265 nm deep-ultraviolet light-emitting diodes with over 90 mW output power via an AlN hybrid nanostructure , 2015 .

[19]  Christoph Reich,et al.  Low-threshold stimulated emission at 249 nm and 256 nm from AlGaN-based multiple-quantum-well lasers grown on sapphire substrates , 2014 .

[20]  Hideo Kawanishi,et al.  TM-mode lasing and anisotropic polarization properties of AlGaN multiple quantum well lasers in deep-ultraviolet spectral region , 2007, SPIE OPTO.

[21]  K. B. Nam,et al.  Unique optical properties of AlGaN alloys and related ultraviolet emitters , 2004 .

[22]  T. Egawa,et al.  In-plane structural anisotropy and polarized Raman-active mode studies of nonpolar AlN grown on 6H-SiC by low-pressure hydride vapor phase epitaxy , 2010 .

[23]  S. Denbaars,et al.  Microstructure and enhanced morphology of planar nonpolar m-plane GaN grown by hydride vapor phase epitaxy , 2005 .

[24]  Theeradetch Detchprohm,et al.  Demonstration of transverse-magnetic deep-ultraviolet stimulated emission from AlGaN multiple-quantum-well lasers grown on a sapphire substrate , 2015 .

[25]  Zlatko Sitar,et al.  High internal quantum efficiency in AlGaN multiple quantum wells grown on bulk AlN substrates , 2015 .

[26]  K. Thonke,et al.  Growth and Characterization of AlN and AlGaN Epitaxial Films on AlN Single Crystal Substrates , 2011 .

[27]  Z. Sitar,et al.  Homoepitaxial AlN thin films deposited on m-plane ( 11¯00) AlN substrates by metalorganic chemical vapor deposition , 2014 .

[28]  Z. Sitar,et al.  Strain relaxation by pitting in AlN thin films deposited by metalorganic chemical vapor deposition , 2013 .

[29]  Shun Lien Chuang,et al.  k.p method for strained wurtzite semiconductors , 1996 .