. (2005). Complex quantum dot arrays formed by combination of self-organized anisotropic strain engineering and step engineering on shallow patterned substrates. Journal of Applied Physics, 97(1), 014304-1/5. [014304]. DOI: 10.1063/1.1823578 General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. One-dimensional (In,Ga)As quantum dot (QD) arrays are created on planar singular, vicinal, and shallow mesa-patterned GaAs (100) substrates by self-organized anisotropic strain engineering of an ͑In, Ga͒As/ GaAs quantum wire (QWR) superlattice template in molecular beam epitaxy. On planar singular substrates, highly uniform single QD arrays along ͓0−11͔ are formed. On shallow ͓0−11͔ and [011] stripe-patterned substrates, the generated type-A and -B steps distinctly affect the surface migration processes which are crucial for QWR template development, i.e., strain-gradient-driven In adatom migration along [011] and surface-reconstruction-induced Ga/ In adatom migration along ͓0−11͔. In the presence of both type-A and -B steps on vicinal substrates misoriented towards [101], the direction of adatom migration is altered to rotate the QD arrays. This establishes the relationship between self-organized anisotropic strain and step engineering, which is exploited on shallow zigzag-patterned substrates for the realization of complex QD arrays and networks with well-positioned bends and branches, exhibiting high structural and optical quality.
InAs quantum dash (QDH) and quantum dot (QD) lasers grown by molecular beam epitaxy on InP substrate are studied. The laser active zones with multiple stacked layers exhibit lasing wavelength at 1.55μm. On these devices, the experimental threshold current density reaches its minimum value for a double stacked QDH/QD structure. Other basic laser properties such as gain and quantum efficiency are compared. QD lasers exhibit better threshold current densities but equivalent modal gain per layer than QDH. Finally, the analysis of the modal gain on QD lasers shows a promising potential for improvement.
Purpose – The purpose of this paper is to analyze and summarize the development of science and technology (S & T) policies in China from a government-driven perspective in chronological order. To develop knowledge-based economy, China enacts a range of S & T policies since “Reform and Open Policy” started in 1978. Furthermore, it investigates the overall effects of these S & T policies on university-industry linkages (UILs). Design/methodology/approach – This paper conducts an analysis framework of S & T policies in historical sequence to explain how government drives UILs to stimulate technological progress and economic growth in China. Findings – More than a site for high-quality workforce education and knowledge spread, universities as an important part of national innovation are required to participate in economic activities. Considering that most Chinese universities are national, S & T policies with particular regard to university technology transfer would be more important and essential. This research finds that S & T policies enacted by government have made critical contributions to UILs in economic transition period, such as improving academic faculty, enhancing university–industry collaborations and supporting university spin-off formation. The experiences of China suggest that government should enact more effective S & T policies in the knowledge-based economy era. Practical implications – First, universities need to educate high-level human resources that are important for economic growth and social development. Second, universities need to engage in R & D activities and enhance their collaboration with industries, such as consulting services, research contracts with industry, patent licensing and other general knowledge commercial mechanisms. Third, universities also can directly transfer commercial knowledge to start up new businesses by itself or in partnership with industrial sectors. Without doubt, a series of S & T policies or programs enacted by China’s government to drive entrepreneurship continuously played critical role in the UILs over the past 26 years. Originality/value – This paper is a pioneering work on how S & T policies enacted by government drive UILs to stimulate technological progress in transitional China.
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