Application Of Position Sensitive Detectors Research Articles

Strain detection in crystalline heterostructures using bidimensional blocking patterns of channelled particles

Strain is a critical parameter affecting the growth and the performance of many semiconductor systems but, at the same time, the accurate determination of strain profiles in heterostructures can be challenging, especially at the nanoscale. Ion channelling/blocking is a powerful technique for the detection of the strain state of thin films, normally carried out through angular scans with conventional particle detectors. Here we report the novel application of position sensitive detectors for the evaluation of the strain in a series of AlInN/GaN heterostructures with different compositions and thicknesses. The tetragonal strain is varied from compressive to tensile and analysed through bidimensional blocking patterns. The results demonstrate that strain can be correctly quantified when compared to Monte Carlo channelling simulations, which are essential because of the presence of ion steering effects at the interface between the layer and the substrate. Despite this physical limitation caused by ion steering, our results show that full bidimensional patterns can be applied to detect fingerprints and enhance the accuracy for most critical cases, in which the angular shift associated to the lattice distortion is below the critical angle for channelling.

The Application of PSD in Vibration Measurment

Position Sensitive Detector (PSD) is a new type of photoelectric position sensor. Compared with traditional CCD, PSD has high position resolution, simple circuit and fast response. Operational principle of PSD and how it can be used in vibration system are firstly shown in this paper. Based on the MCU, a vibration measurement system using a BOS-PSD0220 type sensor is designed. The system is then experimentally measured at the most sensitive area of PSD. The result is compared with data calculated by MATLABLE, which demonstrates PSD is a good choice for vibration measurement.

Application of position sensitive detector for the electron detachment cross-sections measurement

In this paper, we report our improved detection system based on a micro-channel plate (MCP) position sensitive detector, which could simplify our experiment process of the electron detachment cross-sections measurement in negative ion–gas collisions. The operating parameters of MCP are investigated thoroughly, and we present the dependence of the pulse height distributions (PHD) of the anode signals on MCP bias voltage, incident beam energy, incident beam intensity, and incident ion species. The optimum parameters, such as bias voltage of the MCP, the threshold of the electronics and incident ions intensity, are determined. The saturation curve of MCP is also shown. Finally, we give the single electron detachment cross-sections of H − and C − in collision with N 2 obtained using the new position sensitive detection system. Consistency with other available experiment results shows the reliability of the new detection system.

Characterisation of 1D opto-electronic sensors and their application to angular self-centring probes for machine-tool verification

In this paper the application of position sensitive detectors (PSD) as measuring systems for self-centring probes is explained. Self-centring probes are part of a new technique to perform machine-tools (MT) geometrical verification in a faster way than the traditional one (laser interferometry). These probes were initially designed, developed and manufactured using optical sensors (linear encoders) as internal measuring system. This kind of sensors provided a high resolution and accuracy and very good results in the calibrations of the probes and in their final use. However, they made the size and the cost of the probes too high. In order to improve these characteristics, a low-cost LED + PSD combination has been studied as an alternative measuring system. The results of these studies are presented in this paper, including studies of repeatability and characterisation of the LED + PSD system. The influence of the light spot size and form, the distance between LED and PSD and their relative orientation in linear and angular measuring have been analysed. Different calibration techniques have been developed and applied to these sensors in order to optimise their accuracy in linear and angular measurements. Some possible configurations of the measuring system inside the probe have been studied. Finally, the system has been mounted inside a self-centring probe. A final calibration of the system has been carried out and several correction techniques have been applied. The behaviour of the probe has been tested mounting both measuring systems: linear encoders and LED + PSD.

Detectors for thermal neutrons

The characteristics, limits and adequate applications of position sensitive detectors for thermal neutrons are described.

Application of Position Sensitive Detectors for Neutron Diffraction Texture Analysis of Hematite Ore

Texture means the orientation distribution of the many crystallites in a polycrystalline sample with respect to a reference system on the sample, for example the rolling direction in steel. Texture has to be distinguished from preferred orientation observed in laboratory-made powder samples. Preferred orientation is just a nuissance in the experiment and must be corrected in the ensuing analysis, for example by the formula given by March and published by Dollase Preferred orientation we find commonly in samples containing plate-like crystal flakes. This is again to be distinguished from a non-random particle distribution in the powder samples prepared for diffraction experiments. This effect is always present, also for example in NBS silicon, even if only to a. very small degree (see for example Will et. al). It must and can easily be corrected for in the final least-squares calculation.