Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
Measurement results from an avalanche amplifying pnCCD for single photon imaging
Introduction
The MPI Semiconductor Laboratory together with PNSensor have developed CCDs with back illumination, full depletion and pn-junctions in every active element. They have outstanding characteristics: high-speed readout with up to 1100 frames/s, wide spectral sensitivity from the near infrared to X-ray energies of 25 keV with quantum efficiencies above 90% from 0.3 to 11 keV [1] and between 80% and 100% in the visible range, radiation hardness, and low noise. The applications include X-ray focal plane instrumentation (e.g. on the XMM-Newton and the future eROSITA satellites) and high speed optical imaging (e.g. for High Time Resolution Astrophysics [5]).
The concept of a novel CCD with an electron-multiplying readout is presented. Every CCD column features a passively quenched avalanche cell designed to collect signal electrons from the depleted detector volume (refer to Section IV of [2] for the technological details). The avalanche anode is directly coupled to the gate of an FET realized on-chip, which provides a low impedance coupling to the external amplification stage. The pixel-structure has been derived from pnCCDs and was optimized for lowest leakage current and for compatibility with the avalanche structures. All advantages of pnCCDs are maintained and include an anti-reflective-coating (ARC) applied to maximize quantum efficiency in an application specific wavelength range. A proof of principle production of the new avalanche diode has already been completed successfully, results are published in Refs. [2], [3].
Section snippets
The avalanche pnCCD: general concept
The device concept is based on the combination of a back-illuminated pnCCD with an avalanche cell as the readout node for each column. Referring to Fig. 1, two main regions can be distinguished. The pixellated sensitive area consists of a three-phase CCD structure where all active elements are reverse-biased pn-junctions for low-noise operation. By proper biasing and switching of the registers, signal charge in each column is shifted toward the corresponding readout node. This is an avalanche
Proof of principle tests on X-ray pnCCD in avalanche technology
Although avalanche CCDs share many features with X-ray pnCCDs produced so far, they are substantially new devices. This is because in order to meet the new technological constraints dictated by the realization of the avalanche cell, some major changes in the device topology were adopted. This fact led to the necessity of testing the basic device functionality, a task which is not easily accomplished by using an avalanche-based readout. Dedicated test structures were therefore designed and
Avalanche amplifying pnCCDs under test
Before testing the device in its full functionality, some preliminary investigations had to be made.
Summary and outlook
In this paper we have shown the results from preliminary tests of a new device that aims at imaging single photons in the optical range. The device concept and design is based on the established pnCCD technology developed at the Semiconductor Laboratory of the Max-Planck-Institut. Thanks to a double-sided processing and fully depleted silicon bulk, the outstanding properties of pnCCDs in terms of high quantum efficiency and low leakage current are maintained. Moreover, the single photon
Acknowledgements
We would like to acknowledge Prof. M. Sampietro and Dr. G. Ferrari of the Politecnico di Milano and Dr. M. Porro for the competent support provided during the measurements of transistor noise spectra.
The project was supported by the Johannes-Heidenhain-Stiftung.
References (6)
Proceedings of SPIE
(2007)- P. Holl et al., A new high-speed, single photon imaging CCD for the optical, in: Conference record of IEEE Nuclear...
- C. Merck et al., Back illuminated drift silicon photomultiplier as novel detector for single photon counting, in:...
Cited by (1)
Single-photon imaging for astronomy and aerospace applications
2011, Springer Series in Optical Sciences