Date of Completion

9-23-2014

Embargo Period

9-21-2015

Advisors

Mohammed H. Tehranipoor, Domenic Forte

Field of Study

Electrical Engineering

Degree

Master of Science

Open Access

Campus Access

Abstract

In this thesis, a ZnO/Zn1-xMgxO based quantum cascade laser (QCL) is proposed as a candidate for generation of THz radiation at room temperature. The effect of spontaneous and piezoelectric polarizations are used to investigate THz generation. In addition, we compare absorption coefficient, optical gain, optical output power and WPE of GaN/InxGa1-xN, GaN/AlxGa1-xN and ZnO/Zn1-xMgxO quantum structures calculated using an envelope function framework. The modification of the band energies due to polarization and its effect on the generated THz radiation is explored. The structural and material properties, field dependence of the THz lasing frequency, and generated power are reported for a resonant phonon ZnO/Zn0.95Mg0.05O QCL emitting at 5.27 THz. The theoretical results are compared with those from GaN/InxGa1-xN and GaN/AlxGa1-xN QCLs of similar geometry. Higher calculated optical output powers [PZnMgO = 2.89 mW (nonpolar) at 5.27 THz, 2.75 mW (polar) at 4.93 THz] are obtained with the ZnO/Zn0.95Mg0.05O structure as compared to GaN/Al0.05Ga0.95N QCLs [PAlGaN= 2.37 mW (nonpolar) at 4.67 THz and 2.29 mW (polar) at 4.52 THz]. Furthermore, a higher WPE is obtained for ZnO/ZnMgO QCLs [24.61% (nonpolar) and 23.12% (polar)] when compared to GaN/AlGaN structures [14.11% (nonpolar) and 13.87% (polar)]. These results show that ZnO/ZnMgO material is optimally suited for THz QCLs.

Major Advisor

A.F. Mehdi Anwar

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