Fast Photodetector with Intrinsic Amplification: Avalanche Photodiode Array
Sensors, Devices and Components
- Fast readout and processing
- Internal amplification of low intensity radiation
- Small pixel size possible
- High and homogenous sensitivity
- Fast spatially resolved detection of low-intensity soft X-Rays
- Fast imaging of visible photons
- Real time precision spectroscopy
- Particle tracking in high energy physics experiments
Avalanche Photodiodes (APD) are well proven components for amplified photon detection that are used in fast responding detectors at low photon flux. However, the possibilities of constructing an array of APD detectors are limited due to the necessary protective structures to avoid edge breakdowns. The latter are caused by high electric fields due to the doping profile. State of the art APD arrays avoid edge breakdowns by reducing the electric field towards the edge, which consequently limits the sensitivity. Therefore, they fail to meet the requirements of sufficient isolation between pixels, the suppression of edge breakdowns and a homogenous amplification over the entire detector.
A new monolithic Avalanche Photodiode array has been developed to overcome the aforementioned shortcomings and to further expand the application possibilities of APDs.
According to the invention and its novel approach, the distribution of the electric field and hence the amplification is constant over the entire array and does not change at the pixel edges. The cross-section of a possible implementation of this concept is shown in figure 1. The radiation enters the detector through the p-doped entrance window and is absorbed in the multiplication region 1. As the generated charge carriers follow the electric field towards the anode, they are further multiplied via impact ionization in the highly p-doped multiplication region 2. In the subsequent region, the field drop region, the electric field strength is reduced below the critical value for charge multiplication. In order to ensure inter pixel isolation with minimal amplification field disturbances, the contact implants of each pixel as well as their isolation are located in the region of reduced electric field. Different isolation arrangements have been tested successfully.
As no decrease of the electric field at the pixel edge is needed, the sensitivity is almost constant over the entire pixel surface. Hence pixel sizes can be chosen very low without restricting the detection performance.
PCT (WO2020201189A1), DPMA (DE102019204701)
- Ref.-No.: 1201-5750-BC (367.1 KiB)
Dr. Bernd Ctortecka, M. Phil.
Phone: +49 89 / 29 09 19-20