Unconventional Growth Mechanism for Monolithic Integration of III鈥揤 on Silicon

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• 作者：Kar Wei Ng ; Wai Son Ko ; Thai-Truong D. Tran ; Roger Chen ; Maxim V. Nazarenko ; Fanglu Lu ; Vladimir G. Dubrovskii ; Martin Kamp ; Alfred Forchel ; Connie J. Chang-Hasnain
• 刊名：ACS Nano
• 出版年：2013
• 出版时间：January 22, 2013
• 年：2013
• 卷：7
• 期：1
• 页码：100-107
• 全文大小：558K
• 年卷期：v.7,no.1(January 22, 2013)
• ISSN：1936-086X

文摘

The heterogeneous integration of III鈥揤 optoelectronic devices with Si electronic circuits is highly desirable because it will enable many otherwise unattainable capabilities. However, direct growth of III鈥揤 thin film on silicon substrates has been very challenging because of large mismatches in lattice constants and thermal coefficients. Furthermore, the high epitaxial growth temperature is detrimental to transistor performance. Here, we present a detailed studies on a novel growth mode which yields a catalyst-free (Al,In)GaAs nanopillar laser on a silicon substrate by metal鈥搊rganic chemical vapor deposition at the low temperature of 400 掳C. We study the growth and misfit stress relaxation mechanism by cutting through the center of the InGaAs/GaAs nanopillars using focused ion beam and inspecting with high-resolution transmission electron microscopy. The bulk material of the nanopillar is in pure wurtzite crystal phase, despite the 6% lattice mismatch with the substrate, with all stacking disorders well confined in the bottom-most transition region and terminated horizontally. Furthermore, InGaAs was found to be in direct contact with silicon, in agreement with the observed crystal orientation alignment and good electrical conduction across the interface. This is in sharp contrast to many III鈥揤 nanowires on silicon which are observed to stem from thin SiN_x, SiO₂, or SiO₂/Si openings. In addition, GaAs was found to grow perfectly as a shell layer on In_0.2Ga_0.8As with an extraordinary thickness, which is 15 times greater than the theoretical thin-film critical thickness for a 1.5% lattice mismatch. This is attributed to the core鈥搒hell radial geometry allowing the outer layers to expand and release the strain due to lattice mismatch. The findings in this study redefine the rules for lattice-mismatched growth on heterogeneous substrates and device structure design.

Keywords:

nanoneedle; nanowire; nanopillar; III鈭扸 on Si; laser; critical thickness; transmission electron microscopy