CMPL SEMICON
National Institute of Physics
University of the Philippines - Diliman
The laboratory has a variety of optical characterization tools to assess the quality and performance of the samples and devices fabricated in the lab. Techniques such as transmission and reflection spectroscopy, together with photocurrent and photoreflectance are some of the experiments used in characterizing thin films and various heterostructures. Further more, the laboratory houses the Solar Testing Facility which allows the standard characterization of solar cell devices.
Solar Testing Facility
The National Solar Testing Facility housed in the National Institute of the Philippines is dedicated to developing a standardized characterization for solar cell devices. It consists of a current-voltage curve tracing station and the quantum efficiency setup. The two characterization are necessary in determining the efficiency of a solar cell device. The facility currently offers its services to academic and industrial researchers. The facility was created under the project “Nanostructured Solar Energy Devices” funded by the Department of Science and Technology
Scanning Electron Microscopy
The Scanning Electron Microscope (SEM) is a microscopy technique used in obtaining high resolution images of objects with the use of a high vacuum system, granted by DOST in 1997 for characterization purposes. The SEM works by focusing a beam of high energy electrons to scan the surface of a conducting sample under observation, secondary electrons from its surface are reflected back to a detector which generates a micrographs of the object. This image can be magnified up to approximately 100000 times which can be used in surface topography analysis at the nanoscale level. Additional features of the CMPL's SEM is the Energy Dispersive Spectroscopy which is used to determine chemical composition of the sample through an X-Ray detector.
X-ray Diffraction
The X-ray diffractometer (XRD) is a non-destructive, characterization machine capable of determining the structural properties of different materials(i.e. thin films, powder samples, semiconductors). These structural properties include crystal structure, chemical composition, and the presence of stress and strain. The Condensed Matter Physics Laboratory (CMPL) has an X-ray Diffractometer (Model: Bede D3 System) of a Bragg-Brentano geometry set-up which involves movement in the detector along θ and the stage of the sample with its X-ray source fixed. With this set-up, the characterization method involves reflection geometry diffractions. This technique is mainly based on the elastic scattering of X-rays from the electron clouds of the individual atoms in the system.
Characterization
Raman Spectroscopy
Raman spectroscopy is an optical characterization technique for observing the vibrational modes of a material. The CMPL-Semicon houses a microRaman setup with a backscattering geometry utilizing a 514nm Argon ion laser. The Raman spectra of a material may enable one to determine its composition, stress/strain state, crystalline quality, crystalline symmetry and orientation.
Reflection, Transmission, UV-Vis, and Photoluminesence Spectroscopy
Optical spectroscopy is a non-destructive and versatile tool for the investigation of the electronic properties of semiconductor material and structures. It is a way of testing the quality and efficiency of MBE-grown layers and predicting the performance of fabricated devices. Included among the widely-used characterization techniques used in CMPL are photoluminescence, transmission, reflectance and photoreflectance, and photocurrent spectroscopy.
Hall Measurement
Hall measurement is a widely used characterization technique to determine the electrical properties of a semiconductor by exploiting the Hall effect using a magnet. The key feature of this machine is its ability to determine the resistivity and Hall resistance, the mobility of carriers, and the sheet and carrier concentration of an n-type semiconductor.
Current Voltage Characteristics
The I-V curve tracer allows the characterization of electrical properties of a semiconductor material or device. It is used to calculate the resistance of the device. It may also be used to test or check the response of a photovoltaic device to illumination.
WYKO Interferometer
The Wyko Inferometer, given by Hitachi, is used primarily in the measurement of the depth or roughness of samples by giving a 3D image of the exposed surface for characterization purposes. Phase-shift interferometry (PSI) and vertical-shift interferometry (VSI) are the techniques used in the measurement. PSI uses light of single wavelength and is better used for samples with smooth surface while VSI uses multiple wavelengths of light and is used for measurements of samples with varying heights. The Wyko Interforemeter also generates image with better resolution than the optical microscopy.
TeraHertz Time Domain Spectroscopy
Terahertz (THz) radiation is better known as the part of the electromagnetic spectrum in the range 0.3–3 THz. THz technology is rapidly advancing and with this, is opening up great possibilities for basic research as well as for potential applications in spectroscopy and imaging of materials and biological/medical samples. It can be utilized as a non-contact and non-destructive technique of characterization. THz radiation has some traits of both microwaves and visible light. This peculiar characteristic of THz radiation makes it useful for different applications and gives an edge over other frequency regimes in the electromagnetic spectrum.
The NIP established the first THz-Time Domain Spectroscopy (THz-TDS) setup in the Philippines recently to cater to the vast potential in this emerging field of research with using of the Ultrafast Laser Facility housed in the institute.
