Browsing by Author "Lin, J. -C."

Now showing 1 - 2 of 2

Hidden lattice instabilities as origin of the conductive interface between insulating LaAlO3 and SrTiO3
(2016-09-01)
Lee, P. W.
;
Singh, V. N.
;
Guo, G. Y.
;
Liu, H. -J.
;
Lin, J. -C.
The metallic interface between insulating LaAlO3 and SrTiO3 opens up the field of oxide electronics. With more than a decade of researches on this heterostructure, the origin of the interfacial conductivity, however, remains unsettled. Here we resolve this long-standing puzzle by atomic-scale observation of electron-gas formation for screening hidden lattice instabilities, rejuvenated near the interface by epitaxial strain. Using atomic-resolution imaging and electron spectroscopy, the generally accepted notions of polar catastrophe and cation intermixing for the metallic interface are discounted. Instead, the conductivity onset at the critical thickness of 4-unit cell LaAlO3 on SrTiO3 substrate is accompanied with head-to-head ferroelectric-like polarizations across the interface due to strain-rejuvenated ferroelectric-like instabilities in the materials. The divergent depolarization fields of the head-to-head polarizations cast the interface into an electron reservoir, forming screening electron gas in SrTiO3 with LaAlO3 hosting complementary localized holes. The ferroelectriclike polarizations and electron-hole juxtaposition reveal the cooperative nature of metallic LaAlO3/SrTiO3.
White-light emissions from p-type porous silicon layers by high-temperature thermal annealing
(2009-01-01)
Tsai, W. -C.
;
Lin, J. -C.
;
Huang, K. -M.
;
Yang, P. -Y.
;
Wang, S. -J.
In this study, the white-light emissions, including red, green and blue colors, appearing on the same porous silicon samples are originally introduced by a thermal-annealing method. The SEM, FTIR, and PL are discussed for different annealing temperature cases. The FTIR is used to monitor the chemical bonding structures of the PS samples under different annealing temperatures. The results show that the variation of chemical bonding relates to the variation of the emission wavelength. The emission intensities of the blue-green-light components are enhanced with the increase of annealing temperature. The PL spectra cover the entire visible region under the excitations of He-Cd laser beam, and a strong white-light emission can be observed by the naked eye at room temperature. Copyright (C) EPLA, 2009