Visible Electroluminescence from Al-Porous Silicon Reverse Bias Diodes Formed on the Base of Degenerate N-Type Silicon

1994 ◽  
Vol 358 ◽  
Author(s):  
S. Lazarouk ◽  
V. Bondarenko ◽  
P. Pershukevich ◽  
S. La Monica ◽  
G. Maiello ◽  
...  
Keyword(s):  
Porous Silicon ◽  
Reverse Bias ◽  
Light Emission ◽  
Electrochemical Etching ◽  
Forward Bias ◽  
Applied Bias ◽  
Light Emitting ◽  
Type Silicon ◽  
Silicon Devices ◽  
Preparation Conditions

ABSTRACTWe demonstrate current induced visible light emission from Schottky junctions between aluminium electrodes and porous silicon formed by electrochemical etching of degenerate n+ -type silicon. HF concentration and anodizing current were chosen to yield preparation conditions in the transition region between electropolishing and porous silicon formation regimes. The light emitting diodes were formed by magnetron sputtering of aluminum on the porous silicon surface. Visible electroluminescence (EL) was recorded when dc or ac voltages larger than 4 V were applied between the aluminium electrodes. The visible EL appears in the dark, at the edge of the electrodes at a reverse bias of 5-6 V. The intensity of emitted light increases with applied voltage; at applied bias higher than 7 V the light emitted was observable by the naked eye at normal daylight. Compared to forward bias solid state contact porous silicon devices, the structure has an increased stability (after 100 hours of continuous operation under a 7 V reverse bias, no appreciable modification was observed in emission intensity). The main features of this electroluminescence are very similar to the ones observed under avalanche breakdown of silicon p-n junctions.

Theory of Porous Silicon Injection Electroluminescence

1992 ◽  
Vol 283 ◽  
Author(s):  
H. Paul Maruska ◽  
F. Namavar ◽  
N. M. Kalkhoran
Keyword(s):  
Porous Silicon ◽  
Light Emission ◽  
Forward Bias ◽  
Interface States ◽  
Light Emitting ◽  
Long Term Stability ◽  
Quantum Confinement Effects ◽  
Current Path ◽  
Yellow Orange ◽  
P Type

ABSTRACTWe discuss the operation of porous silicon light-emitting diodes prepared as heterojunctions between n-type In2O3:Sn (ITO) and p-type silicon nanostructures, exhibiting quantum confinement effects. The transparent ITO affords light emission through the top surface of the device, as well as providing passivation and hence long term stability. We describe a model for the injection of minority carrier electrons into the porous silicon regions, which results in the emission of yellow-orange DC electroluminescence. A detailed study of the forward bias current-voltage characteristics of the devices will be given, which allows calculations of the densities of interface states. A tendency to pin the hole fermi energy near the neutral level, φ0, is shown to control the extraction of majority carriers. Methods for improving LED efficiency by alleviating a parasitic shunt current path through interface states will be addressed.

Influence of Different Atmospheres on the Life Time of Porous Silicon Light-Emitting Devices

2002 ◽  
Vol 737 ◽  
Author(s):  
B.R. Jumayev ◽  
H.L. Tam ◽  
K.W. Cheah ◽  
N.E. Korsunska
Keyword(s):  
Porous Silicon ◽  
Reverse Bias ◽  
Present Report ◽  
Forward Bias ◽  
Life Time ◽  
Visible Range ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Cu Alloy ◽  
Metal Diffusion

ABSTRACTIn present report, we investigated the degradation processes in porous silicon light-emitting devices (LED) in different atmospheres (O2, N2, air and vacuum) by photoluminescence (PL), electroluminescence (EL), lifetime (LT) and I-V characteristic measurements as well as by Energy Dispersive X-ray Spectroscopy (EDS). The contacts were made by evaporation of Au and Au/Cu alloy. The LEDs emit in visible range at forward and reverse bias. As a rule, full width at half maximum of EL spectrum is wider than that of PL spectrum. The bias direction of applied voltage during degradation change EL, PL, I-V characteristics, and LT of the LEDs. At forward bias, LT degradation is less than that in reverse bias.The degradation of LEDs during forward bias did not produce any change in the spectral shape of EL and PL. At reverse bias, degradation led to red shift in the peak of EL and PL. The results show that the lifetime of LEDs with Au contact is longer than Au-Cu. Operating in different atmospheres, the LT in vacuum is longest and is more than 100 hours in reverse bias at room temperature.Possible mechanisms of degradation of LEDs are discussed. It is proposed that degradation is connected mainly with two processes: oxidation and metal diffusion. It is shown that the oxygen and metal in ionic state can diffuse quickly. Hence, in forward bias, the diffusion of metal would dominate, and in reverse bias, diffusion of oxygen dominates.

LUMINESCENCE BEHAVIOR AND MECHANISM OF LIGHT-EMITTING POROUS SILICON

1994 ◽  
Vol 08 (02) ◽  
pp. 69-92 ◽  
Author(s):  
XUN WANG
Keyword(s):  
Porous Silicon ◽  
Blue Light ◽  
Light Emission ◽  
Energy State ◽  
Surface Recombination Velocity ◽  
Luminescence Spectroscopy ◽  
Carrier Injection ◽  
Blue Light Emission ◽  
Light Emitting ◽  
Si Nanostructures

In this review article, we give a new insight into the luminescence mechanism of porous silicon. First, we observed a “pinning” characteristic of photoluminescent peaks for as-etched porous silicon samples. It was explained as resulting from the discontinuous variation of the size of Si nanostructures, i.e. the size quantization. A tight-binding calculation of the energy band gap widening versus the dimension of nanoscale Si based on the closed-shell Si cluster model agrees well with the experimental observations. Second, the blue-light emission from porous silicon was achieved by using boiling water treatment. By investigating the luminescence micrographic images and the decaying behaviors of PL spectra, it has been shown that the blue-light emission is believed to be originated from the porous silicon skeleton rather than the surface contaminations. The conditions for achieving blue light need proper size of Si nanostructures, low-surface recombination velocity, and mechanically strong skeleton. The fulfillment of these conditions simultaneously is possible but rather critical. Third, the exciton dynamics in light-emitting porous silicon is studied by using the temperature-dependent and picosecond time-resolved luminescence spectroscopy. A direct evidence of the existence of confined excitons induced by the quantum size effect has been revealed. Two excitation states are found to be responsible for the visible light emission, i.e. a higher lying energy state corresponding to the confined excitons in Si nanostructures and a lower lying state related with surfaces of Si wires or dots. A picture of the carrier transfer between the quantum confined state and the surface localized state has been proposed. Finally, we investigated the transient electroluminescence behaviors of Au/porous silicon/Si/Al structure and found it is very similar to that of an ordinary p-n junction light-emitting diode. The mechanism of electroluminescence is explained as the carrier injection through the Au/porous silicon Schotky barrier and the porous silicon/p-Si heterojunction into the corrugated Si wires, where the radiative recombination of carriers occurs.

scholarly journals Electroluminescence and photo-response of inorganic halide perovskite bi-functional diodes

Nanophotonics ◽  
2018 ◽  
Vol 7 (12) ◽  
pp. 1981-1988 ◽  
Author(s):  
Ning Li ◽  
Ying Suet Lau ◽  
Yanqin Miao ◽  
Furong Zhu
Keyword(s):  
Visible Light ◽  
High Speed ◽  
Light Emission ◽  
Forward Bias ◽  
Green Light ◽  
Visible Light Communication ◽  
Light Emitting ◽  
Response Characteristics ◽  
Photo Response ◽  
Halide Perovskite

AbstractIn this work, we report our efforts to develop a novel inorganic halide perovskite-based bi-functional light-emitting and photo-detecting diode. The bi-functional diode is capable of emitting a uniform green light, with a peak wavelength of 520 nm, at a forward bias of >2 V, achieving a high luminance of >103 cd/m2 at 7 V. It becomes an efficient photodetector when the bi-functional diode is operated at a reverse bias, exhibiting sensitivity over a broadband wavelength range from ultraviolet to visible light. The bi-functional diode possesses very fast transient electroluminescence (EL) and photo-response characteristics, e.g. with a short EL rising time of ~6 μS and a photo-response time of ~150 μS. In addition, the bi-functional diode also is sensitive to 520 nm, the wavelength of its peak EL emission. The ability of the bi-functional diodes for application in high speed visible light communication was analyzed and demonstrated using two identical bi-functional diodes, one performed as the signal generator and the other acted as a signal receiver. The dual functions of light emission and light detection capability, enabled by bi-functional diodes, are very attractive for different applications in under water communication and visible light telecommunications.

Structural, Surface Morphological and Photoluminescence Properties of Nanostructured Porous Silicon Material for Optoelectronics Application

2012 ◽  
Vol 584 ◽  
pp. 290-294 ◽  
Author(s):  
Jeyaprakash Pandiarajan ◽  
Natarajan Jeyakumaran ◽  
Natarajan Prithivikumaran
Keyword(s):  
Porous Silicon ◽  
Current Density ◽  
Light Emission ◽  
Electrochemical Etching ◽  
Light Emitting Diode ◽  
Radiative Transition ◽  
Sem Images ◽  
Optoelectronic Application ◽  
Gap Opening ◽  
P Type

The promotion of silicon (Si) from being the key material for microelectronics to an interesting material for optoelectronic application is a consequence of the possibility to reduce its device dimensionally by a cheap and easy technique. In fact, electrochemical etching of Si under controlled conditions leads to the formation of nanocrystalline porous silicon (PS) where quantum confinement of photo excited carriers and surface species yield to a band gap opening and an increased radiative transition rate resulting in efficient light emission. In the present study, the nanostructured PS samples were prepared using anodic etching of p-type silicon. The effect of current density on structural and optical properties of PS, has been investigated. XRD studies confirm the presence of silicon nanocrystallites in the PS structure. By increasing the current density, the average estimated values of grain size are found to be decreased. SEM images indicate that the pores are surrounded by a thick columnar network of silicon walls. The observed PL spectra at room temperature for all the current densities confirm the formation of PS structures with nanocrystalline features. PL studies reveal that there is a prominent visible emission peak at 606 nm. The obtained variation of intensity in PL emission may be used for intensity varied light emitting diode applications. These studies confirm that the PS is a versatile material with potential for optoelectronics application.

Photoluminescence and Photoluminescence Excitation Mechanisms for Porous Silicon and Silicon Oxynitride

1999 ◽  
Vol 588 ◽  
Author(s):  
Xingsheng Liu ◽  
Jesus Noel Calata ◽  
Houyun Liang ◽  
Wangzhou Shi ◽  
Xuanyin Lin ◽  
...  
Keyword(s):  
Porous Silicon ◽  
Blue Light ◽  
Light Emission ◽  
Luminescence Center ◽  
Silicon Oxynitride ◽  
Photoluminescence Excitation ◽  
Oxide Layers ◽  
Light Emitting ◽  
Light Excitation ◽  
Excitation Mechanisms

AbstractThrough a comparative study of the light emission and light excitation property of porous silicon (PS) and Si oxide, photoluminescence (PL) and photoluminescence excitation (PLE) mechanisms for blue-light-emitting PS are analyzed. Strong blue light (445nm) and ultraviolet light (365nm) emission from silicon-rich silicon oxynitride films at room temperature were observed. An analysis of the PL and PLE spectra of PS and Si oxide indicated that for blue-light emission from PS, there are two types of photoexcitation processes: photo-excitation occurring in nanometer Si particles (NSP's) and in the Si oxide layers covering NSPs, and radiative recombination of electron-hole pairs taking place in luminescence centers (LCs) located on the interfaces between NSP's and Si oxide and those inside Si oxide layers. The PL spectra of silicon-rich silicon oxynitride films implies that the PL originated from some LCs in SiOx and SiOxNy:H, while PLE spectra indicates that photoexcitation occurs in NSPs, SiOx and SiOxNy:H. The 365 nm band is attributed to the former two photoexcitation processes and the 445 nm one to the third process. As such, the quantum confinement/luminescence center model appears to be a satisfactory model in explaining the experimental results.

Effect of Electrolyte Volume Ratio on Electroluminescence of Porous Silicon Nanostructures (PSiNs) Intensity

2013 ◽  
Vol 686 ◽  
pp. 49-55
Author(s):  
M. Ain Zubaidah ◽  
N.A. Asli ◽  
Mohamad Rusop ◽  
Saifollah Abdullah
Keyword(s):  
Porous Silicon ◽  
Light Emission ◽  
Light Emitting Diode ◽  
Volume Ratio ◽  
Visible Range ◽  
Silicon Nanostructures ◽  
Etching Time ◽  
Light Emitting ◽  
Flat Screen ◽  
P Type

For this experiment, the main purpose of this experiment is to determine the electroluminescence of PSiNs samples with optimum electrolyte volume ratio of photo-electrochemical anodisation. PSiNs samples were prepared by photo-electrochemical anodisation by using p-type silicon substrate. For the formation of PSiNs on the silicon surface, a fixed current density (J=20 mA/cm2) and 30 minutes etching time were applied for the various electrolyte volume ratio. Volume ratio of hydrofluoric acid 48% (HF48%) and absolute ethanol (C2H5OH), HF48%:C2H5OH was used for sample A (3:1), sample B (2:1), sample C (1:1), sample D (1:2) and sample E (1:3). The light emission can be observed at visible range. The effective electroluminescence was observed for sample C. Porous silicon nanostructures light–emitting diode (PSiNs-LED) has high-potential device for future flat screen display and can be high in demand.

Film Preparation Conditions and Characterization of co-Deposited Tungsten Doped Zinc Oxide Phosphor

1999 ◽  
Vol 558 ◽  
Author(s):  
Jasleen Bombra Sobti ◽  
V. Bhatia ◽  
P. M. Babuchna ◽  
Mark H. Weichold
Keyword(s):  
Zinc Oxide ◽  
Blue Light ◽  
Light Emission ◽  
Optoelectronic Device ◽  
Flat Panel Displays ◽  
Phosphor Material ◽  
Light Emitting ◽  
Preparation Conditions ◽  
Device Applications ◽  
Work Done

ABSTRACTNeed for efficient blue light emitting source for optoelectronic device applications such as flat panel displays has made the research in luminescent material ever so important. Tungsten doped zinc oxide (ZnO:W) has been identified as a blue light emitting phosphor exhibiting cathodoluminescence near 490 nm. This paper details work done on ZnO:W phosphor preparation conditions for efficient light emission from the phosphor. Material characterization to identify the possible source of blue light emission will also be discussed.

ZnO Nanowire/p-GaN Heterojunction LEDs

2007 ◽  
Vol 1018 ◽  
Author(s):  
Heiko O. Jacobs ◽  
Jesse Cole ◽  
Amir M. Dabiran ◽  
Heiko O. Jacobs
Keyword(s):  
Reverse Bias ◽  
Forward Bias ◽  
Zno Nanowires ◽  
Hole Injection ◽  
Zno Nanowire ◽  
Defect States ◽  
Light Emitting ◽  
Current Voltage ◽  
Distinct Color ◽  
Two Peaks

AbstractThis article reports forward and reverse biased emission in vertical ZnO nanowire/p-GaN heterojunction light emitting diodes (LEDs) grown out of solution on Mg-doped p-GaN films. The electroluminescence spectra under forward and reverse bias are distinctly different. Forward bias showed two peaks centered around 390 nm and 585 nm, while reverse bias showed a single peak at 510 nm. Analysis of the current-voltage characteristics and electroluminescence spectra is presented to determine the transport mechanism and location of electron hole recombination. Reverse bias transport and luminescence are attributed to hot-hole injection from the ZnO nanowires into the GaN film through tunneling breakdown. Forward bias transport and luminescence are attributed to hole injection from the GaN into the ZnO and recombination at defect states inside the ZnO yielding distinct color variations between individual wires. Major resistive losses occurred in the GaN lateral thin film connecting to the vertical ZnO nanowires.

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