Fast Photoluminescence from Porous Silicon

1992 ◽  
Vol 283 ◽  
Author(s):  
V. Petrova-Koch ◽  
T. Muschik ◽  
D. I. Kovalev ◽  
F. Koch ◽  
V. Lehmann
Keyword(s):  
Porous Silicon ◽  
Response Time ◽  
Spectral Range ◽  
Luminescence Band ◽  
Room Temperature ◽  
Internal Surface ◽  
Porous Si ◽  
Time Resolved ◽  
Processed Material ◽  
Defect Luminescence

ABSTRACTTime-resolved studies of the visible photoluminescence in porous silicon with three different coverages of the internal surface are reported. We use aged, naturally oxidized porous Si (oxihydride), rapid thermal processed material (oxide) and samples stored in HF (pure hydride). A new, fast luminescence band in the blue-green spectral range and with response time less than 100 ns is observed at room temperature in each of the samples, although with different intensities. The observations prove that this is not an oxide-defect luminescence. We speculate on mechanisms for the origin of the fast luminescence in nanometer-size crystallites of Si.

Porous Silicon Organic Vapor and Humidity Sensor

1996 ◽  
Vol 459 ◽  
Author(s):  
M. C. Poon ◽  
J.K.O. Sin ◽  
H. Wong ◽  
P. G. Han ◽  
W. H. Kwok ◽  
...  
Keyword(s):  
Porous Silicon ◽  
Response Time ◽  
Schottky Diode ◽  
Room Temperature ◽  
Humidity Sensor ◽  
Ethanol Vapor ◽  
Electrical Contacts ◽  
Diode Structure ◽  
Organic Vapor ◽  
Humidity Change

ABSTRACTThis paper presents new organic vapor sensitive device using anodized porous silicon (PS). The sensor has aluminum (Al)/PS/p-Si/Al Schottky diode structure and sensitivity at room temperature in 2600 ppm acetone, methanol, 2-propanol and ethanol is about 4, 5, 10 and 40 times respectively. The sensitivity in 800–2600 ppm ethanol vapor is 2 to 40 times. The diode sensor can be converted into an Al/PS/Al resistor sensor by switching the electrical contacts, and the sensitivity is about 500 times for a humidity change of 43–75%. All sensors have response time of about 0.5 min. The sensitivity is stable with time and the PS sensor can be integrated into VLSI Si devices to form novel microelectronic systems.

Er-Implanted Porous Silicon: a Novel Material for Si-Based Infrared LEDs

1994 ◽  
Vol 358 ◽  
Author(s):  
Fereydoon Namavar ◽  
F. Lu ◽  
C.H. Perry ◽  
A. Cremins ◽  
N.M. Kalkhoran ◽  
...  
Keyword(s):  
Porous Silicon ◽  
Room Temperature ◽  
Wide Bandgap ◽  
Device Fabrication ◽  
Porous Si ◽  
High Concentration ◽  
Light Emitting ◽  
Novel Material ◽  
Bandgap Semiconductors ◽  
Ir Emission

ABSTRACTWe have demonstrated a strong, room-temperature, 1.54 μm emission from erbium-implanted at 190 keV into red-emitting porous silicon. Luminescence data showed that the intensity of infrared (IR) emission from Er implanted porous Si annealed at ≤ 650°C, was a few orders of magnitude stronger than Er implanted quartz produced under identical conditions, and was almost comparable to IR emission from In0.53Ga0.47As material which is used for commercial IR light-emitting diodes (LEDs).The strong IR emission (much higher than Er in quartz) and the weak temperature dependency of Er in porous Si, which is similar to Er3+ in wide-bandgap semiconductors, suggests that Er is not in SiO2 or Si with bulk properties but, may be confined in Si light-emitting nanostructures. Porous Si is a good substrate for rare earth elements because: 1) a high concentration of optically active Er3+ can be obtained by implanting at about 200 keV, 2) porous Si and bulk Si are transparent to 1.54 μm emission therefore, device fabrication is simplified, and 3) although the external quantum efficiency of visible light from porous Si is compromised because of self-absorption, it can be used to pump Er3+.

Drift Mobility Measurements in Porous Silicon

1996 ◽  
Vol 420 ◽  
Author(s):  
L. Tsybeskov ◽  
C. Peng ◽  
P. M. Fauchet ◽  
Q. Gu ◽  
E. A. Schiff
Keyword(s):  
Porous Silicon ◽  
Response Time ◽  
Room Temperature ◽  
Forward Bias ◽  
Drift Mobility ◽  
Maximum Response ◽  
Forward Bias Voltage ◽  
Maximum Response Time ◽  
Temperature Time ◽  
Applied Forward Bias

AbstractModulated electroluminescence (EL) measurements performed on a series of porous silicon (PSi) diodes are presented. The maximum response time of the devices scales with the square of the PSi layer thickness and inversely with the applied forward bias voltage. These scaling results indicate that the maximum response time is a carrier transit time from which a drift mobility μ of 10−4 cm2/Vs is deduced at room temperature. Time-of-flight transport measurements on PSi are in qualitative agreement with this value for μ in addition, they identify μ as the electron mobility and show that transport is dispersive, in contrast to the interpretation of the modulated EL experiments.

Unimportance of Siloxene in Luminescent Porous Silicon as Determined by Nexafs & Exafs

1993 ◽  
Vol 298 ◽  
Author(s):  
S.L. Friedman ◽  
M.A. Marcus ◽  
D.L. Adler ◽  
Y.-H. Xie ◽  
T.D. Harris ◽  
...  
Keyword(s):  
Fine Structure ◽  
Porous Silicon ◽  
Room Temperature ◽  
Emission Spectra ◽  
Porous Si ◽  
X Ray ◽  
Absorption Fine ◽  
X Ray Absorption ◽  
Room Temperature Luminescence ◽  
Combined Data

AbstractNear-edge-- and extended--x-ray absorption fine structure measurements, as well as luminescence excitation and emission spectra, were obtained from samples of porous Si and siloxene. Contrary to a recently proposed explanation for the room temperature luminescence in porous Si, the combined data indicate that siloxene is not principally responsible for the observed effect.

Photoluminescence Properties of Er-Doped Porous Silicon

1995 ◽  
Vol 405 ◽  
Author(s):  
U. Hömmerich ◽  
X. Wu ◽  
F. Namavar ◽  
A. M. Cremins-Costa ◽  
K. L. Bray
Keyword(s):  
Porous Silicon ◽  
Room Temperature ◽  
Power Dependence ◽  
Photoluminescence Properties ◽  
Porous Si ◽  
Temperature Quenching ◽  
Photoluminescence Study ◽  
Visible Luminescence ◽  
Excitation Mechanisms ◽  
Er Doped

AbstractWe present a photoluminescence study of erbium implanted into porous silicon (Er:PSi) with two different Si porosities, a) Er:PSi with a purple appearance and b) with a green-yellow appearance. Er was implanted with a dose of 1×1015 Er/cm2 at 380 keV and annealed at 650°C for 30 minutes. Room-temperature 1.54μm Er3+ emission was observed from both samples. The emission from purple Er:PSi was four times stronger than that from green-yellow Er:PSi. In contrast, visible luminescence from green-yellow Er:PSi was found to be stronger than that from purple Er:PSi. Temperature quenching and power dependence was investigated to elucidate the excitation mechanisms of Er3+ in porous silicon. The results support a correlation between nanostructures of porous Si and 1.54 μm Er3+ luminescence.

Auger Effect Seen in the Porous Silicon Fast Luminescent Band

1998 ◽  
Vol 536 ◽  
Author(s):  
R. M'ghaïeth ◽  
I. Mihalcescu ◽  
H. Maâref ◽  
J. C. Vial
Keyword(s):  
Porous Silicon ◽  
Room Temperature ◽  
Dominant Role ◽  
Nonlinear Excitation ◽  
Time Resolved ◽  
Fast Red ◽  
Silicon Nanocrystallites ◽  
New Feature ◽  
Auger Effect ◽  
Time Resolved Photoluminescence

AbstractTime resolved photoluminescence (PL) measurements are performed on oxidized and fresh porous silicon at room temperature. Comparing the evolution of the nanosecond time delayed PL in both cases, a new feature of the PL spectra is identified: the fast-red band, present as well in fresh or aged samples. The nonlinear excitation intensity dependence of this component is described by a simple model where, the Auger effect inside isolated silicon nanocrystallites plays the dominant role.

Photoluminescence from Single Porous Silicon Chromophores

1998 ◽  
Vol 536 ◽  
Author(s):  
M. D. Mason ◽  
G. M. Credo ◽  
K. D. Weston ◽  
S. K. Buratto
Keyword(s):  
Porous Silicon ◽  
Room Temperature ◽  
Porous Si ◽  
Vibronic Structure ◽  
Passivating Layer ◽  
Si Nanoparticles ◽  
Si Nanocrystal ◽  
Quantum Confined

AbstractWe spatially isolate and detect the luminescence from individual porous Si nanoparticles at room temperature. Our experiments show a variety of phenomena not previously observed in the emission from porous Si including a distribution of emission wavelengths, resolved vibronic structure, random spectral wandering, luminescence intermittency and irreversible photobleaching. Our results indicate that the emission from porous Si nanoparticles originates from excitons in quantum confined Si, strongly influenced by the surface passivating layer of the Si nanocrystal.

Intense Visible Luminescence from Thermally-Oxidized Porous Silicon

1992 ◽  
Vol 283 ◽  
Author(s):  
S. Miyazakj ◽  
K. Shiba ◽  
K. Sakamoto ◽  
M. Hirose
Keyword(s):  
Porous Silicon ◽  
Light Emission ◽  
Excitation Power ◽  
Thermally Grown Oxide ◽  
Localized States ◽  
Porous Si ◽  
Time Resolved ◽  
Visible Luminescence ◽  
Oxidized Porous Silicon ◽  
The Ideal

ABSTRACTPhotoluminescence from porous silicon oxidized at 800 or 900°C in an N2 +O2 gas mixture has been investigated. The ideal passivation of the porous Si surface with thermally grown oxide results in stable, intense visible-light emission. The steady-state and time-resolved luminescence measured as functions of temperature and excitation power have indicated that a possible pathway for the light emission is the radiative recombination through localized states.

Carrier Dynamics in Porous Silicon: from the Femtosecond to the Second

1994 ◽  
Vol 358 ◽  
Author(s):  
Philippe M. Fauchet
Keyword(s):  
Porous Silicon ◽  
Time Domain ◽  
Room Temperature ◽  
Auger Recombination ◽  
Excitation Intensity ◽  
Carrier Dynamics ◽  
Time Resolved ◽  
Oxidized Porous Silicon ◽  
Red Luminescence ◽  
Absorption Measurements

ABSTRACTThe luminescence in red-emitting porous silicon exhibits a distribution of lifetimes in the μsec time domain at room temperature and in the msec time domain at cryogenic temperatures. However, the luminescence and carrier dynamics in porous silicon display transients that vary from much less than 1 psec to ∼ 1 sec, depending on the measurement conditions and sample preparation. We have investigated the carrier dynamics in porous silicon by two time-resolved techniques. The blue photoluminescence of oxidized porous silicon has been measured with 100 ps time resolution as a function of the oxidation method, emission wavelength, excitation intensity and measurement temperature. The blue luminescence has a distinct origin from the well-studied red luminescence and we attribute it to defects in the oxide. Femtosecond photoinduced absorption measurements have been performed on thin red-emitting porous silicon films. The wavelength and intensity dependence of the recovery are interpreted in terms of trapping and of Auger recombination at high excitation intensity. Our results also show conclusively that red-emitting porous silicon is not a direct gap semiconductor.

Photophysical properties of N719 and Z907 dyes, benchmark sensitizers for dye-sensitized solar cells, at room and low temperature

2021 ◽  
Vol 23 (10) ◽  
pp. 6182-6189
Author(s):  
Dariusz M. Niedzwiedzki
Keyword(s):  
Solar Cells ◽  
Low Temperature ◽  
Optical Spectroscopy ◽  
Room Temperature ◽  
Photophysical Properties ◽  
Dye Sensitized Solar Cells ◽  
Time Resolved ◽  
Dye Sensitized ◽  
Sensitized Solar Cells

Photophysical properties of N719 and Z907, benchmark Ru-dyes used as sensitizers in dye-sensitized solar cells, were studied by static and time-resolved optical spectroscopy at room temperature and 160 K.

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