Surface photovoltage in semiconductors under sub-band-gap illumination: continuous distribution of surface states

1999 ◽  
Vol 69 (4) ◽  
pp. 409-413 ◽  
Author(s):  
L. Szaro ◽  
J. Rębisz ◽  
J. Misiewicz
Keyword(s):  
Band Gap ◽  
Continuous Distribution ◽  
Surface States ◽  
Surface Photovoltage

Direct Measurement and Identification of Nonradiative Processes in ZnO Nanocrystallines by Combining Photoacoustic Spectroscopy with Surface Photovoltage Spectroscopy

2011 ◽  
Vol 361-363 ◽  
pp. 831-839
Author(s):  
Feng Yang ◽  
Kui Ying Li ◽  
Jing Zhi Sun ◽  
Mang Wang ◽  
Gang Wu ◽  
...  
Keyword(s):  
Band Gap ◽  
Photoacoustic Spectroscopy ◽  
Direct Detection ◽  
Surface States ◽  
Relative Energy ◽  
Surface Photovoltage ◽  
Main Peak ◽  
Relaxation Processes ◽  
Photoacoustic Spectrum ◽  
Nonradiative Processes

Nonradiative transitions (NRTs) are relaxation processes competing with radiative process. In light emitting diodes and room temperature laser devices, NRTs lower the emission efficiency. In order to prohibit these processes, better understanding is practically needed. But nowadays knowledge of NRTs comes from the analyses of the steady-state and time-resolved photoluminescence spectra, which are indirect evidences because of their radiative nature. Here we report a direct detection of nonradiative processes of ZnO nanocrystallines by combination of photoacoustic spectroscopy (PAS) with field-induced photovoltaic spectroscopy (FISPS) methods. In photoacoustic spectrum of ZnO nanocrystals, a main feature centered at 374 nm and a shoulder feature at 441 nm have been recorded. The surface photovoltage spectrum (SPS) displays a main peak at about 364 nm, which is assigned to band-gap transition. And the FISPS spectrum shows a main feature at 380 nm and a pronounced shoulder at 450 nm. The relative energy of the PAS main feature locates at about 0.1 eV lower than that of band-gap, and the relative energy of the PAS main and shoulder features locates at 60 meV higher than that of FISPS main and shoulder features. These energy spaces are in good consistent with the exciton binding energy reported for ZnO nanostructures. Thus we tentatively ascribe the NRTs to the trapping of the photogenerated excitons to the surface states of ZnO nanocrystallines.

New method for determination of energy distribution of surface states in the semiconductor band-gap: XPS measurements under biases

1994 ◽  
Vol 92 (3) ◽  
pp. 249-254 ◽  
Author(s):  
Hikaru Kobayashi ◽  
Toshio Mori ◽  
Kenji Namba ◽  
Yoshihiro Nakato
Keyword(s):  
Energy Distribution ◽  
Band Gap ◽  
Surface States ◽  
New Method

Luminescence of II-VI Semiconductor Nanoparticles

2014 ◽  
Vol 222 ◽  
pp. 1-65 ◽  
Author(s):  
B.P. Chandra ◽  
V.K. Chandra ◽  
Piyush Jha
Keyword(s):  
Band Gap ◽  
Data Storage ◽  
Quantum Confinement Effect ◽  
Ultrafine Particle ◽  
Surface States ◽  
Emission Spectra ◽  
Volume Ratio ◽  
Blue Shift ◽  
Band Gap Energy ◽  
Molecular Engineering

Nanoparticle or an ultrafine particle is a small solid whose physical dimension lies between 1 to 100 nanometers. Nanotechnology is the coming revolution in molecular engineering, and therefore, it is curiosity-driven and promising area of technology. The field of nanoscience and nanotechnology is interdisciplinary in nature and being studied by physicists, chemists, material scientists, biologists, engineers, computer scientists, etc. Research in the field of nanoparticles has been triggered by the recent availability of revolutionary instruments and approaches that allow the investigation of material properties with a resolution close to the atomic level. Strongly connected to such technological advances are the pioneering studies that have revealed new physical properties of matter at a level intermediate between atomic/molecular and bulk. Quantum confinement effect modifies the electronic structure of nanoparticles when their sizes become comparable to that of their Bohr excitonic radius. When the particle radius falls below the excitonic Bohr radius, the band gap energy is widened, leading to a blue shift in the band gap emission spectra, etc. On the other hand, the surface states play a more important role in the nanoparticles, due to their large surface-to-volume ratio with a decrease in particle size (surface effects). From the last few years, nanoparticles have been a common material for the development of new cutting-edge applications in communications, energy storage, sensing, data storage, optics, transmission, environmental protection, cosmetics, biology, and medicine due to their important optical, electrical, and magnetic properties.

Surface states in one-dimensional photonic band gap structures

Vacuum ◽  
2001 ◽  
Vol 63 (1-2) ◽  
pp. 177-183 ◽  
Author(s):  
B Djafari-Rouhani ◽  
E.H El Boudouti ◽  
A Akjouj ◽  
L Dobrzynski ◽  
J.O Vasseur ◽  
...  
Keyword(s):  
Band Gap ◽  
Photonic Band Gap ◽  
Surface States ◽  
One Dimensional ◽  
Photonic Band Gap Structures ◽  
Photonic Band

Quantification of electronic band gap and surface states on FeS2(100)

2013 ◽  
Vol 618 ◽  
pp. 53-61 ◽  
Author(s):  
F.W. Herbert ◽  
A. Krishnamoorthy ◽  
K.J. Van Vliet ◽  
B. Yildiz
Keyword(s):  
Band Gap ◽  
Surface States ◽  
Electronic Band ◽  
Electronic Band Gap
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