Suhaila Isaak

Design and process simulation of p-well guard ring Si Avalanche Photodiode

The design, simulation and characterization of Silicon Avalanche Photodiode (SAPD) that can be implemented with SILVACO TCAD tool are presented. This SAPD design used the diffusion of p-wells to create a low p layer doping density as the guard ring to prevent the premature breakdown at the edge of the device. The result demonstrated that the proper gap length between p-wells to create the guard ring allows SAPD to work in the Geiger mode. This showed that by developing a low-doped guard ring at the edge of the junction, it will reduce the electric field, minimize the avalanche current and the edge breakdown can be prevented. In this paper, the SAPD with square shape active area of 2 × 2 μm2 and low doped p-well guard ring has VBD of 27 V and avalanche current of 0.85 pA.

A Flexible Optical Sensor for Microalbuminuria Spectroscopy

Zarina Mohd Noh*, Abdul Rahman Ramli, Marsyita Hanafi, M Iqbal Saripan, Ridza Azri Ramlee 1,2,3,4 Department of Computer and Communication Systems Engineering, Faculty of Engineering, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia 1,5 Fakulti Kejuruteraan Elektronik dan Kejuruteraan Komputer, Universiti Teknikal Malaysia Melaka (UTeM), Hang Tuah Jaya, 75450 Durian Tunggal, Melaka, Malaysia

Controlled defect on multilayer graphene surface by oxygen plasma

The study pertaining defect fabrication of graphene has gained interest nowadays. To date, the fabrication of the defect using reactive ion etching on the oxygen flow rate has not been adequately studied. In this work, fabrication defect on multilayer graphene using reactive ion etching at 30 sccm and 50 sccm oxygen flow rates as a controlled parameter. The other parameters such as pressure, exposure time and power are set as well. The resistance of the exposed multilayer graphene devices at 30 sccm and 50 sccm are respectively 38 and 49 times higher than the non-exposed device. The increased oxygen flow rate in the reactive ion etching deteriorates the crystalline quality of the multilayer graphene thus declines its function as a device. It is suggested that only low oxygen flow rate is to be used to fabricate small amount of defect for the controlled defect purposes.

A Linear Array passively quenched Single Photon Avalanche Diode

The integrated circuit design of Single Photon Avalanche Diode (SPAD) with quenching circuit in CMOS is highly desirable photon detection at high rates, but low counting rates constrain image acquisition rates and dynamic range. The characterization should primarily define the dead time of quenching SPAD circuit in order to estimate the SPAD performance prior fabrication. This paper reports the development and characterization of the mathematical model SPAD on passively quenched SPAD circuit with ballast resistor. An improved model in defining the dead time (tD) response for SPAD is used to characterize the performance of 8×1 passively quenched SPAD array. The time response for both quenching and recharging time are developed for 180 nm depletion layer which means low voltage technology. Hence that, the 8×1 passively SPAD array circuit is designed by using Silterra 180nm CMOS technology for uncorrelated time measurements with on-chip 4-bit counter to improve the counting rate. The passive quenching circuit design on-chip would enable the capability to perform at higher speed, which is more than 100 kHz. In addition, are presented in this paper.