In this paper we present modification of angular photoresponse of InGaAsN-based photodiode with applied polymer (IPDIP) three-dimensional (3D) woodpile structure. 3D woodpile structure was prepared as effective diffractive element for using in optoelectronic devices with possibility of direct application on a chip surface. 3D woodpile structure was prepared using laser lithography by direct laser writing process. The effect of woodpile structure on angular photoresponse structure was investigated from goniophotometer measurements. Spatial modulation of light coupling into the photodiode chip with applied 3D woodpile structure was documented for irradiation by broad-band green light.
Progress in nanotechnologies accelerated the polymer based photonics, where simple and cheap solutions often bring comparable and sometimes also novel interesting results. Good candidates are polymer photoresists and siloxane materials with unique mechanical and optical properties. We present laser lithography as efficient tool for fabrication of different three-dimensional (3D) structures embedded in polydimethylsiloxane (PDMS) membranes. Presented concept of PDMS based thin membranes with 3D structures works as an effective diffraction element for modification of radiation pattern diagram of light emitting diodes and changes also the angular photoresponse of photodiodes. All these results were demonstrated on two types of 3D structures – spheres arranged in cubic lattice and woodpile structure.
Over the last few years, ternary and quaternary semiconductor compounds containing (Ga, In) and (N, As) elements
become subject of many studies. Both, indium and nitrogen, lowers the band gap of gallium arsenide, but their influence
on lattice parameter is compensated. As a result it is possible to deposit epitaxial layers of 1 eV , or less, material which
is matched to GaAs substrate. GaAs technology is well known and much cheaper than more sophisticated phosphorus
alloys. Optoelectronic devices composed of dilute nitrides materials can be widely used as a telecommunication lasers,
photodetectors or even photovoltaic cells.
Investigated samples were performed using atmospheric-pressure MOVPE system with AIXTRON AIX200 R-and-D
reactor. GaNAs layers were deposited as bulk layers, while GaInNAs material grown as bulk and additionally as
quantum wells with GaAs barriers. Gallium arsenide substrates were utilized.
Studies were performed utilizing Raman spectroscopy at room temperature. Phonons were excited using 514 nm Ar+
laser. Characteristic for such structures GaN-like local vibrational mode was observed to change its position with
changing nitrogen concentration. GaAs-like longitudinal optic phonon also was investigated. As a result an attempt to
measure nitrogen concentration in mentioned materials using Raman spectroscopy was performed.
Heterostructures of GaInNAs/GaAs multiple quantum wells were characterized by high resolution x-ray diffraction.
Complexity and stress compensating effect of such quaternary alloys cause many characterization problems. One of the
most important issue is determination of composition of the material, which cannot be performed utilizing only one
characterization method. That is why structural analysis had to be related with optical measurements which give different
information correlated with composition. A comparison of theoretical calculations of energy band gap with energy of
transitions in GaInNAs QWs from photoluminescence or contactless electro-reflectance measurements supplement the
results of HRXRD and gives complete information about the structure required as a feedback to develop technology of
heterostructures epitaxial growth.
Dilute nitride (In, Ga)(As, N) alloys grown on GaAs substrate are a very attractive materials for optoelectronics. In this
work we compare the optical properties of (In, Ga)(As, N)/GaAs triple quantum well grown by atmospheric pressure
metal organic vapour phase epitaxy. As grown and annealed structures were investigated by means of
photoluminescence and contactless electroreflectance spectroscopies. Energies of fundamental transition from each
measurement were determined and compared, moreover the value of Stokes shift was assigned and discussed.
GaAsN and InGaAsN semiconductor alloys with a small amount of nitrogen, so called dilute nitrides, are especially
attractive for telecom lasers and very efficient multijunction solar cells applications. The epitaxial growth of these
materials using MBE and MOVPE is a big challenge for technologists due to the large miscibility gap between GaAs and
GaN. Additionally, elaboration of the growth process of quaternary alloys InGaAsN is more complicated than GaAsN
epitaxy because a precise determination of their composition requires applying different examination methods and
comparison of the obtained results. This work presents the influence of the growth parameters on the properties and alloy
composition of the triple quantum wells 3×InGaAsN/GaAs grown by atmospheric pressure metal organic vapour phase
epitaxy AP MOVPE. Dependence of the structural and optical parameters of the investigated heterostructures on the
growth temperature and the nitrogen source concentration in the reactor atmosphere was analyzed. Material quality of
the obtained InGaAsN quantum wells was studied using high resolution X-Ray diffraction HRXRD, contactless electro-reflectance
spectroscopy CER, photoluminescence PL, secondary ion mass spectrometry SIMS, photocurrent PC and
Raman RS spectroscopies, deep level transient spectroscopy DLTS and transmission electron microscopy TEM.
In this paper application of Si3N4, AlN and polyimide to passivate GaAsN/GaAs MSM photodetectors is presented. The
MSM structures were made on the undoped GaAsN epitaxial layers in which concentration of nitrogen was varied from
1.0 to 2.6 %. The dark and illuminated I-V characteristics of the devices are presented. Comparison of the dark current
value and photoresponse obtained, for selected wavelengths in visible and IR range, from the MSM devices with
different passivation layers is provided. Measurements of the dark current and photoresponse in the unpassivated and
passivated MSM structures allowed to estimate relation between the bulk and surface components of the dark current.
Therefore crystal quality of the epitaxial layers grown in different process conditions could be compared.
The work presents the results of a research carried out with Plasmalab Plus 100 system, manufactured by Oxford
Instruments Company. The system was configured for deposition of diamond-like carbon films by ICP PECVD method.
The deposition processes were carried out in CH4 or CH4/H2 atmosphere and the state of the plasma was investigated by
the OES method. The RF plasma was capacitively coupled by 13.56 MHz generator with supporting ICP generator
(13.56 Mhz). The deposition processes were conducted in constant value of RF generator’s power and resultant value of
the DC Bias. The power values of RF generator was set at 70 W and the power values of ICP generator was set at 300
W. In this work we focus on the influence of DLC film’s thickness on optical, electrical and structural properties of the
deposited DLC films. The quality of deposited DLC layers was examined by the Raman spectroscopy, AFM microscopy
and spectroscopic ellipsometry. In the investigated DLC films the calculated sp3 content was ranging from 60 % to 70 %.
The films were characterized by the refractive index ranging from 2.03 to 2.1 and extinction coefficient ranging from
0.09 to 0.12.
We have investigated deep-level defects in InGaAsN/GaAs 3xQW structures by means of conventional as well as high-resolution
deep level transient spectroscopy (DLTS). The three samples were grown by atmospheric pressure
metalorganic vapour phase epitaxy (AP-MOVPE) in different growth temperatures (566°C, 575°C and 585°C). The DLTS measurements revealed four electron traps E1 (0.17-0.24 eV), E2 (0.36-0.38 eV), E3 (0.46-0.49 eV) and E4 (0.81-0.84 eV) and one hole trap H1(0.8 eV) in our structures. The electron trap E1 was associated with N-related complexes
while the other electron traps with native defects, usually observed in GaAs-based structures EL6, EL3 and EL2,
respectively. Finally, the trap E2 and H1, observed in the structure grown at lowest temperature, were associated with the
same trap, which can act as both an electron and hole trap. It was thus concluded that E2/H1 may be a generation-recombination
center.
The use of the holographic lithography method for sub-nano pattering of photoresist layer deposited on bare sapphire substrate as well as on GaN grown by metaloorganic vapour phase epitaxy on Al2O3 is reported. Positive photoresist Shipley SPR700 was first diluted with photoresist thinner and then spin-coated on prepared substrates to obtain layers of final thickness of 227nm. Thin photoresist layer was exposed in the holographic setup with wavelength of 355nm to produce the surface relief grating. After development SEM observations reveled well-defined valleys and ridges of diffraction grating in SPR700 deposited on gallium nitride layer whereas the whole structure on sapphire was strongly affected by the speckles created by reflection from the unpolished back surface of the sapphire substrate. Latter, we confirmed with transmission spectroscopy, that even small amount of light transmitted through the substrate, which is back reflected by the unpolished back-surface of sapphire, canstrongly disturb nano-sized features in photoresist.
The paper presents the results of work concerning the elaboration of GaN pseudo-bulk technology. The growth mechanism of epitaxial lateral overgrowth (ELO) GaN affected by mask patterns and the MOVPE growth process parameters are presented and discussed. The conditions to obtain full coalescence of isolated stripes leading to pseudo-bulk GaN substrate growth are specified.
Photoreflectance (PR) spectroscopy has been applied to the investigation of Si (delta) -doped AlxGa1-xAs layers grown by metal-organic vapor phase epitaxy on GaAs substrates. Measurements have been carried out on samples with aluminum content of 0,0.35 and 1. The observation of Franz-Keldysh oscillations (FKO) in a number of more than 10 (in the best case) and application of the fast Fourier transformation has allowed us to determine the internal electric field with high accuracy. Thus, the potential barrier between surface and (delta) -doped region has been estimated. Finally, the contribution of heavy and light hole related transitions to the FKO has been resolved.
The results of investigation of PIN and MSM photo detectors fabricated in our Semiconductor Device Laboratory are presented. Discrete chips of PIN and MSM photo detectors and similar photo detectors integrated with a MESFET amplifier within a single MMIC chip were tested and compared. The structures were designed for range of wavelengths from 870nm to 1000nm. To accomplish this, the InxGa1-xAs absorption layer with appropriate cantent of indium has been used as an active layer. All structures have been fabricated using Metal Organic Vapor Phase Epitaxy (MOVPE) growth on GaAs substrates with the use of different buffer and matching layer configuration. I-V and spectral characteristics of the PIN and MSM photo detectors and also MMIC structures with the MSM photo detector were evaluated. Time response to the optical pulse excitation has been measured. All designs were compared from the point of view of their application in the optoelectronic integrated circuits.
The interband transitions in thin epitaxial films grown by metalorganic chemical vapour deposition (MOCVD) have been studied as a function of temperature (1 0-300K) by photoluminescence (PL) and reflectance measurements. In photoluminescence at low temperature bound and free excitons are observed. Temperature dependence of free exciton energies have been studied in reflectance measurement. In the reflectance spectra excitonic interband transitions f9V.4'7C (exciton FX(A)), f7V (upper band)JT7C (exciton FX(B)) and F7"(lower band)I7C (exciton FX(C)) were observed. From temperature dependence of the excitonic spectra the energy gap dependence is determined using both the Varshni E(T)=E(O)-aT2/(T0+T) and Bosse-Einstein E(T)=E(O)-A/[exp(3/T)-1] expressions.
AlxGa1-xN layers with 0.02 xGa1-xN layer grown on it were evaluated by high resolution X-ray measurements, their surface morphology was observed with SEM and Nomarski optical microscope. Electrical properties of the layers were determined by C-V measurements performed at 100 kHz and 1 MHz using mercury probes. The aluminum incorporation into the solid phase during the growth process has been studied. As a result high quality AlxGa1-xN/GaN layers for electronic application have been deposited.
Mariusz Ciorga, Krzysztof Jezierski, Leszek Bryja, Jan Misiewicz, Regina Paszkiewicz, Ryszard Korbutowicz, Marek Panek, Bogdan Paszkiewicz, Marek Tlaczala, Ib Trabjerg
Photoluminescence and reflectance studies of MOVPE grown GaN samples were performed. From reflectance measurements optical constants were calculated by means of Kramers-Kronig analysis in the energy region 0 divided by 6 eV.
In presented work, analysis, classification, and selected methods of solving problems connected with coupling optical fibers to integrated optic structures has been shown. The construction and technology of PIN and MSM type detectors and Mach-Zehnder modulator has been described. Several variants of package constructions have been proposed for optical fibers to optoelectronic devices coupling.
The photoluminescence (PL) spectra of MOCVD-grown GaAs samples have been measured at 10K, and for the most representative sample, PL spectra were recorded from 10 to 150K. Besides of the well-established transitions, a hitherto unreported peak was seen at 1.454 eV. The identification of a line at 1.408 eV is discussed.
Thick intentionally undoped GaAs epitaxial layers grown by LPE from Ga-Bi solution with different contents of Bi in liquid solvent were studied by photoluminescence at temperature T equals 2K. The dependence of photoluminescence spectra on contents of Bi in solution was analyzed.
InGaAs/GaAs quantum wells have been grown in MOCVD system equipped with horizontal Aixtron reactor. Photoreflectance spectra have shown, even at room temperature, sharp heavy and light holes excitonic transitions in quantum wells. The obtained splitting energies have been compared with values derived from theoretical considerations using envelope function model including lattice mismatch-related stress. Heavy and light holes transitions have been identified as excitonic transitions type I and type II, respectively. Photoluminescence measurements have been also done. For quantum wells, transitions between first heavy hole and first electron subbands have been observed. Additionally the temperature dependence of observed transitions have been performed.
Semiconductor light sources and detectors keep the major share of the telecommunication and local area network market. Diode laser and detector structures are also massively produced in the course of many application and research projects. Usually research work includes: understanding physical phenomena governing device performance, device modeling and fabrication. A number of steps however, have to be completed before one can use the device in a real-life system or sell it. To exemplify details of fiber optic detectors and transmitters fabrication, a didactic-purpose fabrication line has been assembled. The following paper presents results of a project aimed at producing some fiber optic telecommunication devices during students laboratory work.
The LBIC method was used to investigate the trapping-recombination centers in GaAs:Si layers grown by MOCVD method. The special test structure was developed and performed. The model which joins the measured signal changes with the presence of trapping centers from substrate (EL2 deep levels) and surface.
Modulator structures fabricated in GaAs/AlGaAs multilayer system offer the advantages of optoelectronic circuits integration and backup of well developed epitaxial layers technology. Fabry-Perot (F-P) waveguide-type modulators have been analyzed and fabricated in MOCVD produced GaAs/AlGaAs structures. Test structures have been developed to obtain the values of material and technological parameters necessary for exact modelling and successful technology development. Theoretical model of F-P modulator has been developed. The output intensity dependencies of F-P modulator on different input parameters are plotted and then obtained characteristics are considered in terms of fabrication technology and modulator applications. With measured electrical parameters, equivalent circuits of electrode structure has been built. The model has been used to analyze the frequency response of the device in the range from DC to RF. Finally, system approach is developed towards the processes of research and fabrication of Fabry-Perot type electro-optic modulator.
Liquid phase epitaxy (LPE) has been carried out from the mixed Ga+Bi solution of different thickness to improve GaAs epilayer surface morphology and the growth process control. The difference between thin and thick solutions has been demonstrated. The process occurring during epitaxy of GaAs layers growth in a non-stationary LPE system from a molten Ga-Bi solution has been studied. Results obtained from thin and thick liquid phase epitaxy has been compared with the diffusion limited compound semiconductor epitaxial growth model. The results revealed that there are two anomalous kinetics growth zones of solvent composition in which the growth rate is unpredictable by diffusion theory of LPE. A model of the LPE growth from Ga-Bi solutions has been suggested, that take into account complex shape of the liquids curve of the Ga-Bi-As system and changes in the mass transfer process occurring in the microinhomogeneous liquid phase. Electrical and optical property of GaAs epitaxial layer grown from mixed Ga-Bi solvent was studied and discussed. The results from two laboratories that used different experimental methods have been compared.
Experimental set-up has been established by using high resolution monochromator as well as He-Ne and Ar multiline lasers. Epitaxial, undoped and doped (Si and Zn) GaAs and GaAlAs layers as well as heterostructures of GaAs/GaAlAs have been grown in atmospheric pressure vertical MOCVD system. Room temperature photoreflectance (PR) have been applied to characterize layers, heterostructures as well as the multiple quantum wells. The surface and interface related PR have been studied by means of Kramers-Kronig analysis. Decomposition of PR spectrum into the spectra connected with surface region and with the interface has been proposed. Modulus of the complex photoreflectance gives us the critical point energy, whereas the phase of this function can be used for a carrier concentration topography.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.