Growth of high-quality ZnMgO epilayers and ZnO∕ZnMgO quantum well structures by radical-source molecular-beam epitaxy on sapphire

Sadofev, Sergey; Blumstengel, S.; Cui, Jian; Puls, J.; Rogaschewski, S.; Schäfer, P.; Sadofyev, Yu. G.; Henneberger, F.

doi:10.1063/1.2034113

Cited by 127 publications

(70 citation statements)

References 17 publications

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“…Note that the low T g allows for the growth . A Mg content of x = 0.35 slightly below the solubility limit was selected for the low refractive index (RI) layer [10] in order to reach a large RI contrast (∆n/n ≈ 10%) while still allowing for stable two-dimensional growth. For the specific layer thicknesses used, the stop band is centered at λ SC = 436 nm and exhibits a spectral width of about 180 meV.…”

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Vertical cavity surface emitting laser action of an all monolithic ZnO-based microcavity

Kalusniak

Sadofev

Halm

et al. 2011

Applied Physics Letters

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We report on room temperature laser action of an all monolithic ZnO-based vertical cavity surface emitting laser (VCSEL) under optical pumping. The VCSEL structure consists of a 2λ microcavity containing 8 ZnO/Zn0.92Mg0.08O quantum wells embedded in epitaxially grown Zn0.92Mg0.08O/Zn0.65Mg0.35O distributed Bragg reflectors (DBRs). As a prerequisite, design and growth of high reflectivity DBRs based on ZnO and (Zn,Mg)O for optical devices operating in the ultraviolet and blue-green spectral range are discussed.Semiconductor lasers operating in the ultraviolet (UV) and blue spectral range have become of great technological importance, e.g., for data storage applications. Compared to the commonly employed edge-emitting devices, vertical cavity surface emitting lasers (VCSELs) offer several advantages such as single mode emission, a circular beam profile, and the possibility for integration into two dimensional arrays. VCSELs based on GaN and its alloys reached a promising stage of development [1] and laser devices working in the strong exciton-photon coupling regime, so called polariton lasers, have been demonstrated at room temperature [2]. In principle, with ZnObased alloys, a similar spectral range can be covered as with the (Al,In,Ga)N heterosystem. Room temperature lasing of (Zn,Cd)O/ZnO quantum well (QW) structures was achieved from UV to green wavelengths [3]. In the strong coupling regime, ZnO was predicted to be even superior due to its high oscillator strength and exciton binding energy [4,5]. However, necessary prerequisites to both VCSELs and polariton lasers are microcavities (MCs) with a high quality factor and good optical quality ZnO active layers. So far only hybrid MCs [6-9] consisting of, e.g., an epitaxially grown GaN-based bottom distributed Bragg reflector (DBR), a ZnO active layer, and a top dielectric DBR have been employed.In this letter, we report on the monolithic growth of ZnO and (Zn,Mg)O based DBRs and MCs by radicalsource molecular beam epitaxy (MBE). With a properly chosen DBR ternary alloy composition, it is possible to obtain high reflectivities with a moderate number of mirror pairs in the range from 375 nm to 500 nm. Finally, we demonstrate an UV emitting all-ZnO VCSEL.The samples are grown in a commercial DCA-450 MBE apparatus equipped with standard metal sources and a radical plasma cell for oxygen. A-plane (1120) sapphire wafers are used as substrates. The (Zn,Mg)O DBRs and MCs containing ZnO/(Zn,Mg)O QWs are grown without interruption at T g = 340 • C with an oxygen limited growth rate of 330 nm/h, which was previously determined from oscillations in the specular beam intensity of in situ reflected high-energy electron diffraction (RHEED) [3]. Note that the low T g allows for the growth

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confidence: 99%

Vertical cavity surface emitting laser action of an all monolithic ZnO-based microcavity

Kalusniak

Sadofev

Halm

et al. 2011

Applied Physics Letters

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“…with the polar c-direction of ZnO lying in the growth plane. Wide ZnO/(Zn, Mg)Obased QWs without QCSE have been successfully grown on the a-plane (11)(12)(13)(14)(15)(16)(17)(18)(19)(20) [13,22,23] or the m-plane (10-10) [24,25].…”

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confidence: 99%

“…ZnO/(Zn,Mg)O QWs have been successfully grown by different techniques such as LMBE [6][7][8][9][10], metalorganic chemical vapor deposition [11,12], and molecular beam epitaxy (MBE) [13][14][15]. Originally sapphire [3] substrates were used.…”

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confidence: 99%

Optical properties of ZnO/(Zn, Mg)O quantum wells

Bretagnon

2014

Turk J Phys

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This paper reviews the optical properties of ZnO/(Zn, Mg)O single quantum wells grown by molecular beam epitaxy. Both heteroepitaxial quantum well growth along the polar c-direction and homoepitaxial quantum well growth on the nonpolar M plane cases are considered. The optical properties of these quantum wells are investigated by using reflectance, continuous wave photoluminescence, and time-resolved photoluminescence spectroscopies. The quantum-confined Stark effect dominates the properties of the excitons for polar quantum wells. The magnitude of the internal electric field that is induced by both spontaneous and piezoelectric polarizations is determined by comparing the experimental results with a variational calculation of excitonic energies and lifetimes. For nonpolar quantum wells, the optical spectra reveal strong in-plane optical anisotropies, as predicted by the group theory. Moreover, the radiative recombination of free excitons is dominating the quantum well photoluminescence even at room temperature.

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“…In order to address high energy ISBT we have chosen a Mg content of x = 0.40, which is close to the solubility limit. 15 As a consequence, the samples exhibit an island-like surface morphology with the average island height of 7 nm and the root mean square roughness of 3.1 nm over a scanning area of 10 × 10 µm 2 .…”

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Tunable intersubband transitions in ZnO/ZnMgO multiple quantum wells in the mid infrared spectral range

et al. 2017

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We report on controllable tuning of intersubband transitions in ZnO/Zn0.60Mg0.40O multiple quantum well structures grown by molecular beam epitaxy on sapphire. The transitions from the first to the second electronic energy state within the conduction band are directly observed by infrared spectroscopy. By variation of the quantum well width, the intersubband transition energies are tuned from 290 to 370 meV. The experimental results are in good agreement with theoretical calculations assuming the presence of internal electric fields of 2 MV·cm−1.

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Growth of high-quality ZnMgO epilayers and ZnO∕ZnMgO quantum well structures by radical-source molecular-beam epitaxy on sapphire

Cited by 127 publications

References 17 publications

Vertical cavity surface emitting laser action of an all monolithic ZnO-based microcavity

Vertical cavity surface emitting laser action of an all monolithic ZnO-based microcavity

Optical properties of ZnO/(Zn, Mg)O quantum wells

Tunable intersubband transitions in ZnO/ZnMgO multiple quantum wells in the mid infrared spectral range

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