D. Berman-Mendoza

Quadrant photodiode for electronic processing

In this work, a photodiode for the visible spectral range, which will be integrated monolithically with CMOS circuits, is presented. Such Optoelectronic Integrated Circuit (OEIC) with high sensitivity in the 400-900 nm spectral range is utilized to realize electronic processing from the light beam position that hit a specific area of the photodetector. The output signals with voltages of 0V and 3 V can be implemented with a controller circuit. By the Using of He-Ne Laser at 633 nm as incident light, the responsivity of the Position Sense Photodetector (PSPD) was 0.35 A/W and the rise and fall time of less than 30 ns were achieved. These parameters were necessaries to achieve the photodiode integration in an industrial 0.5 μm CMOS process, only additional mask was needed in order to block out the threshold voltage implantation in the photo-active region. Therefore both designs of photodiode and the electronic processing circuit separately, are shown here, all design will be integrated monolithically in the same Silicon chip.

Fabrication and electrical characteristics of TFTs based on chemically deposited CdS films, using glycine as a complexing agent

In this work, we report on the fabrication and electrical characteristics of thin film transistors (TFTs) using chemically deposited cadmium sulfide (CdS) thin films as the semiconductor active layer in back-gated devices. The CdS thin films were deposited by the chemical bath deposition (CBD) technique using glycine as the complexing agent. The CdS layers were deposited on SiO2/Si-n substrates and lift-off was used to define the source and drain contacts (Au) on top of these layers. The Si-n wafer with a chromium-gold back contact served as the common gate for the transistors. Several devices with different channel lengths ranging from 10 to 80 μm were fabricated by this process. We studied the properties of the CdS layers deposited by this glycine-based CBD process and the electrical behavior of the transistors as a function of the channel length. The experimental results show that as-deposited CdS are n-type in character and devices exhibit typical pinch-off in drain current versus source–drain voltage (IDS–VDS) curves for several gate voltages. The values of the threshold voltage of the devices were in the range from 8.5 to 8.9 V, depending on the channel length. Channel mobility was between 4.3 and 5.2 cm 2 V −1 s −1 . This research implies that CdS TFTs produced by a simple and low-cost technique could be applicable to electronic devices. (Some figures in this article are in colour only in the electronic version)

Fabrication, characterization, and optimization of an ultraviolet silicon sensor

This work shows the design, fabrication, and optimization of a silicon sensor with an extended sensing range toward the UV region. The main characteristic of this detector is the enlargement of the common silicon detection range to the ultraviolet region (240 to 400 nm). The fabrication process of this detector is compatible with complementary metal oxide semiconductor (CMOS) silicon technology, which makes it cheaper than commercial UV detectors.

Design, fabrication, and characterization of an ultraviolet silicon sensor

In this work a Silicon/Silicon Rich Oxide (SRO) Ultraviolet detector is designed, fabricated and characterized. This device increases the silicon detection range to the ultraviolet region (200-300nm). Besides the fabrication process of this detector is compatible with standard silicon technology that makes it cheaper than commercial UV detectors.

Effect of Au/SiO2 substrate on the structural and optical properties of gallium nitride grown by CVD

The improvement of the growth of thick GaN films using a fused silica wafer covered with a thin gold layer by chemical vapour deposition at 800 ∘C is reported. In order to compare the surface properties, crystalline quality, micromilling performance and luminescence, the characterization of a GaN film grown on a silicon wafer is presented as well. The different morphologies of the surface observed on the GaN films are compared on each substrate and the resulting microstructures are presented in detail. High resolution TEM images of the GaN films show the main crystallographic planes characterizing these structures. The wurtzite structure was determined for each sample using the substrates of Au/SiO2 and Si (100) from the XRD patterns. Also, the re-deposition effect after ion milling of the GaN films is reported. The performance of ionic beam on the surface of the GaN thick films for the geometries patterning of rectangular, circular and annular with two different ion doses was compared. Cathodoluminescence spectra showed that the top surfaces of the samples emit strong UV emissions peaked at 3·35 and 3·32 eV which are related to the Y 4 and Y 6 transitions.

Development, Characterization and optimization of an Ultraviolet Silicon Sensor

In this work the development, characterization and optimization of a silicon sensor with an extended sensing range up to UV is presented. The main characteristic of this detector is that it increases the silicon detection range to the ultraviolet region (240–400 nm). Besides, the fabrication process of this detector is compatible with CMOS silicon technology which makes it cheaper than commercial UV detectors.