Optical polarization in c-plane Al-rich AlN/Al<sub>x</sub>Ga<sub>1-x</sub>N single quantum wells

Tahtamouni, T. M. Al; Lin, J. Y.; Jiang, H. X.

doi:10.1063/1.4737941

Cited by 44 publications

(20 citation statements)

References 23 publications

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“…For laser diode (LD) applications, although the edge emission property of Al-rich Al x Ga 1-x N is considered to be not a problem, TE polarized LDs are generally preferred for practical implementation. By carefully designing the QW structures with reduced QW width, the quantum confinement can be utilized to alter the valence-band order and, consequently promotes TE (E⊥c) polarization in Al-rich Al x Ga 1-x N QWs [72][73][74]. As a result, the transition from E⊥c to E//c may occur at much larger x values.…”

Section: Optical Polarization In C-plane Al-rich Algan Alloys and Qwsmentioning

confidence: 99%

Hexagonal boron nitride for deep ultraviolet photonic devices

Jiang¹,

Lin²

2014

Semicond. Sci. Technol.

135

103

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This paper provides a brief overview on recent advances in tackling the doping and optical polarization issues involved in the development of high performance deep ultraviolet (DUV) light emitting devices. In particular, recent developments in the exploitation of a novel DUV emitter layer structure based on a hexagonal boron nitride (hBN) and AlGaN p-n junction and doping engineering to potentially overcome the intrinsic problem of low p-type conductivity (or low free hole concentration) in Al-rich AlGaN are summarized. By implementing the wide bandgap and highly conductive hBN p-type layer strategy in nitride DUV emitters, p-type conductivities and DUV transparency of the electron blocking layer and p-type contact layer will be dramatically increased. This will significantly improve the free hole injection and quantum efficiency, reduce the operating voltage and heat generation, and increase the device operating lifetime. The growth of undoped and Mg-doped p-type hBN via a metal organic chemical vapor deposition technique has been studied. Furthermore, p-hBN/n-AlGaN p-n junctions have been fabricated and characterized to demonstrate the feasibility and potential of p-hBN/n-AlGaN p-n heterostructure based DUV light emitting devices. Further improvements in material quality, p-type conductivity control and device processing procedures would enhance the properties of these p-n structures, which could ultimately pave the way towards the realization of high efficiency nitride DUV photonic devices.

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Section: Optical Polarization In C-plane Al-rich Algan Alloys and Qwsmentioning

confidence: 99%

Hexagonal boron nitride for deep ultraviolet photonic devices

Jiang¹,

Lin²

2014

Semicond. Sci. Technol.

135

103

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“…The small wavelength variation of $4 nm in the emission wavelengths of these lasers are due to lateral wafer inhomogeneities, which can include variation of strain state, composition, layer thickness, and carrier density. [15][16][17][18][19] As the excitation power density increased, the spectral linewidth narrowed significantly and reached FWHM values of 1.4-2.3 nm at respective maximum excitation power density, which indicated stimulated emission. 2,3 The laser thresholds were estimated to be 280, 250, and 290 kW/cm 2 for the 239-nm, 242-nm, and 243-nm lasers, respectively.…”

mentioning

confidence: 99%

Demonstration of transverse-magnetic deep-ultraviolet stimulated emission from AlGaN multiple-quantum-well lasers grown on a sapphire substrate

Kao

Satter

et al. 2015

Applied Physics Letters

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We demonstrate transverse-magnetic (TM) dominant deep-ultraviolet (DUV) stimulated emission from photo-pumped AlGaN multiple-quantum-well lasers grown pseudomorphically on an AlN/sapphire template by means of photoluminescence at room temperature. The TM-dominant stimulated emission was observed at wavelengths of 239, 242, and 243 nm with low thresholds of 280, 250, and 290 kW/cm2, respectively. In particular, the lasing wavelength of 239 nm is shorter compared to other reports for AlGaN lasers grown on foreign substrates including sapphire and SiC. The peak wavelength difference between the transverse-electric (TE)-polarized emission and TM-polarized emission was approximately zero for the lasers in this study, indicating the crossover of crystal-field split-off hole and heavy-hole valence bands. The rapid variation of polarization between TE- and TM-dominance versus the change in lasing wavelength from 243 to 249 nm can be attributed to a dramatic change in the TE-to-TM gain coefficient ratio for the sapphire-based DUV lasers in the vicinity of TE-TM switch.

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“…The important SOC effect is taken into account in the present calculations. The active layer of DUV optoelectronic devices (LEDs and LDs) usually consists of an Al-rich Al x Ga −x 1 N MQW with a typical thickness of 20∼30 nm [27,59,60], which can be constructed from an ∼20-period WZ AlGaN supercell (∼1.5 nm) generated by × × 3 3 3 primitive cells (see figure 1). Two different Ga distributions are considered here.…”

Section: Calculation Methodsmentioning

confidence: 99%

Enhancement of TE polarized light extraction efficiency in nanoscale (AlN)_m/(GaN)_n(m>n) superlattice substitution for Al-rich AlGaN disorder alloy: ultra-thin GaN layer modulation

et al. 2014

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The problem of achieving high light extraction efficiency in Al-rich Al x Ga −x 1 N is of paramount importance for the realization of AlGaN-based deep ultraviolet (DUV) optoelectronic devices. To solve this problem, we investigate the microscopic mechanism of valence band inversion and light polarization, a crucial factor for enhancing light extraction efficiency, in Al-rich Al x Ga −x 1 N alloy using the Heyd-Scuseria-Ernzerhof hybrid functional, local-density approximation with 1/2 occupation, and the Perdew-Burke-Ernzerhof functional, in which the spin-orbit coupling effect is included. We find that the microscopic Ga-atom distribution can effectively modulate the valence band structure of Al-rich Al x Ga −x 1 N. Moreover, we prove that the valence band arrangement in the decreasing order of heavy hole, light hole, and crystal-field split-off hole can be realized by using nanoscale (AlN) m /(GaN) n (m>n) superlattice (SL) substituting for Al-rich Al x Ga −x 1 N disorder alloy as the active layer of optoelectronic devices due to the ultra-thin GaN layer modulation. The valence band maximum, i.e., the heavy hole band, has p x -and p y -like characteristics and is highly localized in the SL structure, which leads to the desired transverse electric (TE) polarized (E⊥c) light emission with improved light extraction efficiency in the DUV spectral region. Some important band-structure parameters and electron/hole effective masses are also given. The physical origin for the valence band inversion and TE polarization in (AlN) m /(GaN) n SL is analyzed in depth.

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Optical polarization in c-plane Al-rich AlN/Al_xGa_1-xN single quantum wells

Cited by 44 publications

References 23 publications

Hexagonal boron nitride for deep ultraviolet photonic devices

Hexagonal boron nitride for deep ultraviolet photonic devices

Demonstration of transverse-magnetic deep-ultraviolet stimulated emission from AlGaN multiple-quantum-well lasers grown on a sapphire substrate

Enhancement of TE polarized light extraction efficiency in nanoscale (AlN)_m/(GaN)_n(m>n) superlattice substitution for Al-rich AlGaN disorder alloy: ultra-thin GaN layer modulation

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Optical polarization in c-plane Al-rich AlN/AlxGa1-xN single quantum wells

Cited by 44 publications

References 23 publications

Hexagonal boron nitride for deep ultraviolet photonic devices

Hexagonal boron nitride for deep ultraviolet photonic devices

Demonstration of transverse-magnetic deep-ultraviolet stimulated emission from AlGaN multiple-quantum-well lasers grown on a sapphire substrate

Enhancement of TE polarized light extraction efficiency in nanoscale (AlN)m/(GaN)n(m>n) superlattice substitution for Al-rich AlGaN disorder alloy: ultra-thin GaN layer modulation

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Optical polarization in c-plane Al-rich AlN/Al_xGa_1-xN single quantum wells

Enhancement of TE polarized light extraction efficiency in nanoscale (AlN)_m/(GaN)_n(m>n) superlattice substitution for Al-rich AlGaN disorder alloy: ultra-thin GaN layer modulation