Zair Sadygov, JINR, Dubna Igor Zheleznykh, INR, Moscow “Novel Micro-pixel Avalanche PhotoDiodes (M-APDs) and their possible application in physical/astrophysical researches” ARENA Conference, Newcastle, June, 2006 I.Introduction: 1978: First discussions in INR and Lebedev Institute on use of APDs as solid state analogs of the PMTs in DUMAND-type experiments. II 80 th : Development of a new type of APDs with negative local feedback – the metal-resistive layer-semiconductor (MRS) APDs – in INR by Z. Sadygov et al. in the frameworks of the Soviet DUMAND program led by M.A. Markov.

III Since 90 th : Development of new kinds of the Micro- channel/pixel APDs (M-APDs) in INR and JINR. IV Characteristics of the novel M-APDs which were constructed, produced and tested by “Dubna APD” collaboration (JINR – INR – PSI – IP AZ - “Micron” factory): - high signal gain, - high photon detection efficiency, - very good single electron resolution V Conclusion: Prospects for using the M-APDs in different fields of Physics, Astrophysics, Medicine etc.

1977: Neutrino Conference in Baksan (USSR) A. Pomansky, A. Chudakov, P. Budini, A. Tavkhelidze, M. Markov, F. Reines, G. Zatsepin

During Neutrino-77 (in Baksan) and after it (in Moscow) some discussions on DUMAND project took place (F.Reines, A. Roberts, J. Learned, V. Berezinsky, A. Petrukhin …). I asked M. Markov: “You suggested idea of deep underwater neutrino detection in 1960 and we discussed it in that period. Why not to continue discussions again to take part in realization of DUMAND?” Markov asked: “What do you suggest?” “To try to use avalanche photodiodes with optical traps in DUMAND ”. Markov approved such initiative.

Suggestion to use APDs for DUMAND. This paper was also presented at DUMAND-1978, La-Jolla

1978: DUMAND Workshop in La-Jolla. Fred Reines was not interested much in using APDs but he liked an idea to use the Soviet Research Ships in DUMAND.

APDs were successfully used in optical communication since 70 th. Those APDs had usually a sensitive diameter of d=100 micron and a signal gain of G~ Development of large area APDs for other applications (as well as for DUMAND!) had serious problems because of micro heterogeneities inside of semiconductor lattice.

Since 1981, when Markov organized in INR the department of deep underwater neutrino detection, we began to collaborate with the group of Vitaly Shubin (Lebedev Institute) which developed MDS (Metal-Dielectric- Semiconductor) photo receivers. However MDS-structures had some disadvantages (instability etc).

Main problems of semiconductor avalanche devices Very sharp dependence of the multiplication factor M (gain) on applied voltage V ap.; Micro-plasma breakdown phenomena which limit the maximum value of applied voltage, consequently the maximum gain. Micro-plasma phenomena are connected with an appearance of local non-controlled avalanche processes in p-n junctions where the breakdown voltage is lowered because of heterogeneities. There were a few problems that didn’t allow an appearance of large area APDs with high gain (~1000 and more). Here are these problems.

Main problems of semiconductor avalanche devices The mentioned above problems clear seen from the expression of multiplication factor (Miller’s formula): here n – an empirical parameter and usually n ~1 for most of silicon APDs;  V b – a spatial variation of the breakdown voltage overall sensitive area.

Main problems of semiconductor avalanche devices Micro-plasma breakdown in p-n junctions with small-area heterogeneities Conclusion: large spatial variation of breakdown voltage (Vb) don’t allow to get a high gain in conventional p-n junctions.

Two different approaches In the beginning of our activity there were two main approaches to development of new APD’s: Improving purity of semiconductor wafers and using high- technology for production. However this may results in high APD cost; investigation of avalanche process in various multi-layer silicon structure with local suppression effect in order to answer the question: “Is it possible to develop a low- cost APD device on basis of Russian technology?” The second approach has been chosen by our APD-group about 20 years ago. The MRS (metal-resistive layer-silicon) structure has been chosen as a main object of investigation.

Two different approaches to development of new APDs Joint APD group included collaborators from INR (A.Gasanov, Z.Sadygov, et al.) and MELZ (V.Golovin, N.Yusipov). In that time an idea of local feedback in APDs had been discussed at Lebedev Institute (V.Shubin, A.Kravchenko et al.).

Main problems of semiconductor avalanche devices The way to micro-pixel APDs was not easy. This development took about 20 years. Different generations of silicon avalanche structures produced in MOS and MRS type APDs MRS and CCD type APDs CCD and MW type APDs present

A planar Metal -Resistive layer-Semiconductor structure. The first MRS APD Advantages: 1.Simple technology and low cost. Problems: 1. Low yield because of short circuit effect through SiC layer. 2. Limited gain because of charge carriers spreading along Si surface. The first publications on “MRS” type APDs: 1. A.Gasanov, V.Golovin, Z.Sadygov, N.Yusipov. – Technical Physics Letters, v.14, No.8, p.706, (1988). 2. A.Gasanov, V.Golovin, Z.Sadygov, N.Yusipov. – Microelectronics, v.18, No.1, p.88, (1989). 3. Z.Sadygov et al. – IEEE Trans.Nucl.Sci. 43, 3, p.1009, (1996).

The main result. Localization of the avalanche micro-regions results in the unique device properties: high and uniform gain; abnormal behavior of the excess noise factor that may be reduced up to 1 at high gain! The first publications: 1.A.Gasanov, V.Golovin, Z.Sadygov and N.Yusipov.- Russian patent # , application from 09/11/ Z.Sadygov et. al. – SPIE Proc., v.1621, p.158, (1991). An AMPD with individual vertical resistors. Basic version.

A new AMPD with individual surface resistors. Version #1. ( Some people call this version as GMPD, SiPM) Advantages: relatively simple technology; high yield of working sample (~50%). high signal gain (~10 6 ); very good single photo electron resolution. The first publication: Z. Sadygov. “Avalanche detector”.- Russian patent # , application from

Disadvantages of the AMPD of version # 1. Problems: Low geometrical transparency (max. ~ 50%); Limited pixel density (max.~1000 pixel/sq.mm); high capacitance (~60 pF/sq.mm). technology of micro-resistors with so high values (~1M  ) are not accepted in standard microelectronics. Conclusion. An adequate alternative is necessary

An AMPD with individual surface drift channels. Version # 2 Advantages: Standard CMOS technology and high yield of working samples. High signal gain and very good single photoelectron resolution. Problems: Relatively low geometrical transparency (`max ~55-60%). Limited pixel density (max.~ pixel/sq.mm). Conclusion. The next (inverse) type AMPD design is needed. Publication: Z. Sadygov. “Avalanche photo detector”.- Russian patent # , application from 05/30/1996.

An AMPD with deep micro-wells. Version # 3. This version of AMPDs demonstrates the unique parameters: Geometrical transparency/active area %; Quantum efficiency %; Max. gain (today) Equivalent density of pixels per mm sq. Excess noise factor Publication: A patent application # dated

The three advanced versions of AMPDs

The SiPM sample Our design of the AMPD (version 1) Some copies of our AMPD design.

Our design of the AMPD (version 1) The MRS APD sample (CPTA, Russia) Some copies of our AMPD design.

Our design of the AMPD (version 1) The DPPD samples (HAMAMATSU) Some copies of our AMPD design.

Today available AMPD samples for visible and UV light The AMPD parameters you may find in our site:

Possibilities of mass production of the AMPDs of different versions. In February 2005 we agreed with “Mikron” enterprise on joint development and production of the AMPDs of various versions. Now three versions of AMPDs are produced in “Mikron” enterprise. Experimental samples are under testing in scientific and commercial institutions as JINR, INR RAS, PSI, Siemens Medical Solution Inc. USA.

Some results with AMPD samples (v.2) produced by “Mikron” enterprise The AMPD samples are tested in LNP JINR and PSI. Parameters of AMPD samples: wafer – n and p-Si; S=1mm*1mm.

Some results with an AMPD produced by “Mikron” enterprise Photon counting efficiency (PDE) versus on the photon wavelength (measured by Y.Musienko) The Dubna AMPD of version #3 have been tested in PSI and CERN (D.Renker, R. Scheuermann, Y.Musienko, A.Stoykov)

Energy spectra obtained with AMPD-LYSO based detectors. The dashed lines show two-gaussian fits to the 511 keV photopeaks in the spectra. The latest results (E  =511keV)

Development of scintillation detectors, based on avalanche microchannel photodiodes (I. Britvitch et al.)

Future plans : improve working parameters of single element M-APDs for use in visible and UV spectrum; develop matrix M-APDs for application in High Energy Physics and Nuclear medicine; investigate possibilities of creation a supersensitive CCD type matrix on the basis of the M-APD with charge drift channels. We are very interested in collaboration with other Institutions for joint development and application of M-APD devices mentioned above. For more detail information: