/
The group of MOVPE epitaxy and investigations of the properties of nano-heterostructures based on group III nitrides
Equipment for the investigation of physical properties of epitaxial nanostructures based on the III-N compounds, grown by the MOVPE
The automated experimental setup for optical spectroscopy investigations of the A3B5 based nanoheterostructures, created on the basis of MDR-23 monochromator, is intended for photo- (PL) and electroluminescence (EL) spectra measurements, and for reflection, transmission and excitation spectroscopy.
The high-speed versatile fiber-optic spectrometer Avantes 2048 (wavelength range from 190 to 1100 nm) or the MDR-23 monochromator with photodetector, operating in the photon counting or synchronous detection mode, are used for experimental spectra registration.
Various types of the lasers are used for photoluminescence excitation, including: continuous wave He-Cd laser λ = 325 nm, semiconductor laser λ = 405 nm, or pulsed nitrogen laser λ = 337.1 nm. The setup is equipped with the closed-cycle helium cryostat for the PL and EL measurements in the temperature range from 7 to 320 K.
Generic schematic diagram and external view of the optical spectroscopy experimental setup.
 |
 |
The automated setup for spectral characteristics investigations based on “LOMO LUMAM-I2” microscope is intended for micro-electroluminescence and micro-photoluminescence spectra measurements. The registration of the experimental spectra is carried out using the high-speed versatile fiber-optic spectrometer Avantes 3648, which allows measurements in the range of 190 to 1100 nm with high sensitivity and spatial resolution. The automated setup includes X-Y scanning table, which provides two-dimensional displacements in steps of 0.5 microns for the measurements of distribution of the luminescence over the sample surface. For spectra measurements in the temperature range from 80 to 300 K the liquid nitrogen flowing cryostat is used.
External view of the automated measuring complex based on a LOMO microscope.
 |
 |
External view and generic schematic diagram of the automated system for the volt-watt-ampere characteristics measurements:
1. sample; 2. spring contact probes; 3. photodiode; 4. control unit; 5. personal computer; 6. frame.
The forward voltage across the light-emitting diode is supplied through the contact probes. The measurements of the current flowing through the investigated heterostructure is carried out by the personal computer controlled automated control unit. As a result, the L-I-V dependence is recorded, which allows to compare different light-emitting diode structures with each other.
Light-emitting heterostructures based on the InGaN/GaN, emitting in the blue, green, yellow and red wavelength ranges.
 |
 |
 |
 |
The investigation of the electrical parameters of the epitaxial heterostructures: charge carriers concentration ns and drift mobility μ is carried out by Hall effect measurements by four-probe Van Der Pauw method using modernized Bio-Rad HL5200 setup equipped with permanent magnet. The measurements are implemented both at room temperature, as well as, at liquid nitrogen temperature (77K).
External view of the Automated Setup for Hall effect measurement using Van Der Pauw method.
