Polarized Photoluminescence Study on AlGaN of AlGaN/GaN Heterostructure
- PDF / 177,778 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 89 Downloads / 217 Views
0892-FF23-03.1
Polarized Photoluminescence Study on AlGaN of AlGaN/GaN Heterostructure S. Kitagawa1, K. Kosaka1, T. Tsuchiya3, A. Suzuki2,3, T. Araki1,3, and Y. Nanishi1,3 1 Dept. of Photonics, 2Res. Org. of Sci & Eng., Ritsumeikan University, 3 Advanced HF Device R&D Center, R&D Association for Future Electron Devices 1-1-1 Noji-Higashi, Kusatsu, Shiga, 525-8577, Japan E-mail: [email protected] (S. Kitagawa) ABSTRACT Optical properties of tensile strained AlxGa1–xN films of AlxGa1–xN/GaN heterostructures grown on sapphire were investigated by using polarization-resolved photoluminescence spectroscopy. Emissions from AlxGa1–xN with polarization of E//c and E⊥c were obtained at different peak energies. The energy separation of these emissions with polarization was increased linearly with the increase in Al mole fraction of the strained AlxGa1–xN, indicating that the energy separation was due to biaxial strain in the tensile strained AlxGa1–xN. INTRODUCTION Recently GaN and related alloys have been intensely studied because of various attractive physical properties such as high saturation velocity, high breakdown voltage and direct, wide bandgap. Owing to these inherent material properties of GaN, AlxGa1–xN/GaN heterostructures have been employed in high-power and high-frequency electronic devices such as heterostructure field-effect transistors (HFETs) and optical devices such as blue and green light-emitting diodes (LEDs) and blue-violet laser-diodes (LDs). AlxGa1–xN of AlxGa1–xN/GaN heterostructures should have biaxial tensile strain because lattice constant of AlxGa1–xN is smaller than that of GaN. Therefore, fundamental properties on strained AlxGa1–xN of AlxGa1–xN/GaN heterostructures should be different from strain-free AlxGa1–xN bulk properties. Up to now, optical properties on strained GaN have been well studied [1-4]. On the other hand, there are few studies focusing on strained AlxGa1–xN. Thus, it is important to understand fundamental properties of strained AlxGa1–xN in detail. In this paper, we characterized, for the first time, polarization in the strained AlxGa1–xN of AlxGa1–xN/GaN heterostructure by using polarization-resolved photoluminescence (PL) spectroscopy.
0892-FF23-03.2
EXPERIMENTAL DETAILS In this work, we present the results of the optical studies of strained AlxGa1–xN alloys (x = 0.20~0.29) of AlxGa1–xN/GaN heterostructures and free-standing GaN. AlxGa1–xN/GaN heterostructures were grown by metalorganic chemical vapor deposition (MOCVD) on sapphire substrates. All the samples were nominally undoped. Al mole fraction and thickness of AlxGa1–xN determined by X-ray diffraction (XRD) (PANalytical X’Pert MRD) were 0.20~0.29 and ~30 nm, respectively. Free-standing GaN grown by hydride vapor phase epitaxy (HVPE) was also used as a reference. The strain in AlxGa1–xN of AlxGa1–xN/GaN heterostructures was characterized by X-ray reciprocal space mapping (RSM). PL spectra were measured between 5 K~300 K using a closed-cycle helium cryosystem. The 244.0 nm line of a cw second-harmonic genera
Data Loading...
Recommend Documents
Extrinsic Performance Limitations of AlGaN/GaN Heterostructure Field Effect Transistors
186 61 281KB
Photopatterned Films of Discotic Liquid Crystals Demonstrate Polarized Photoluminescence
145 68 46KB
