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Europhysics News (2004) Vol. 35 No. 1 Czochralski's contribution: 50 years on Adam Gadomski, Institute of Mathematics and Physics, University of Technology and Agriculture, Bydgoszcz, Poland The seminal work published by Czochralski in Zeitschrift für physikalische Chemie, received for publication on August of 19th, 1916, but published two years later [1], was an example, rarely met in our days of conciseness and concreteness in presenting research results. On three pages the author reports on his new finding: that a method of pulling metallic monocrystals had been discovered, and had been applied for testing three metals of interest: Sn, Pb, and Zn. This earned him much praise, and in consequence, he is still recognized as one of the fathers of todays semiconductor technology [2] although his method was thoroughly elaborated only for the above metals. It should be noted that Jan Czochralski invented his method during his stay and work in Berlin for the AEG (Allgemeine Elektrizitäts-Gesellschaft) company (Fig. 1) using the AEG lab facilities. He also benefitted from collaboration with a German physicist W. v. Mollendorff [3] and developed much of his knowledge on the crystallography of metals during this time. In order to augment his activity in metal science and technology he moved from Berlin to Frankfurt on Main, where he worked intensively on metallurgical methods to obtain new alloys, as well as on metal based composites, leading to the production of bearings (metal B) [2], and on Al-based wires and contacts in electrotechnics. He also became interested in the durability of materials. However, with his German coworkers, his main focus was on the principles of the metallurgical processes, such as: the role of defects, additives, and specifically of dislocations, in efficiently yielding pure metals and alloys; stress-strain aspects; characteristics of recrystallisation; phase equilibria and transitions associated with their appearances, etc. It is also to be noted that during his time in Frankfurt he proposed in one of his papers "Radiotechnics in Service of Metal Science" in 1925 [4] a kind of radiomicroscope, serving to detect non-metallic inclusions in the outer layer (surface) of a metallic sample. This can in some way be anticipated as a possible prototype of the scanning microscope, with the AFM (atomic force microscopy) included. In the year 1929 he accepted the invitation of the Polish State President, Ignacy Mo´scicki, himself quite a recognised chemist, and moved to Warsaw, where a Warsaw University of Technology professorship in chemistry had been offered to him. Since it was likely that Czochralski had no matriculation, this was only formally possible after the university presented to him the prestigious title of doctor honoris causa. In Warsaw he also became interested in X-ray methods in service of metal structure research, though it is not clear whether he had any Röntgen device at his disposal while working in Warsaw [2].
The main reason for such a division of his mostly scientific activity and also for a certain slowing down was the following: the Warsaw University of Technology's highest council (Senat) suspended him in December 1945 from his professorial duties, strongly referring to certain unproven suspicions that Czochralski had operated against Polish interests from the beginning of World War II [2]. That biased decision was not changed after the war ended and lasted until his death. Although many of us over many years have been taught the way that the semiconductor monocrystals are pulled from the melt by using Czochralski's or, as abbreviated, the CZ method, and at the same time being aware that the method has been readapted and technically expanded by other authors to be the method suitable for semiconductors, we are still surprised to learn from Scheel [5] that recently obtained semiconductor crystals are pulled by another method due to Teal and Little [6]. For an explanation of why Teal and Little's method can be termed an adaptation of CZ method, see [7]. There is no doubt that Jan Czochralski was a personality, satisfying criteria of open-mindedness quite far exceeding his specialised activities. Two examples support this viewpoint. There exists a paper witnessing his activity as a geochemist [8]. While a chemistry professor in Warsaw he was kindly asked by the local authorities of Kcynia to resolve a "burning" problem: Are there any underground resources of natural oil in Kcynia, and in its surroundings (Pal/uki region), or is there something else behind it? His answer after investigation was: There are no underground oil resources there, and the fluid that wets the nearby grounds comes from long-existing storage places for fuel, tar, lubricants and other, mostly liquid, materials, where the barrels containing them, neither tight nor free of corrosion, have systematically polluted all the surroundings by creating over many years sewage areas of high pollution. There is also information that points to Czochralski's wide-ranging activity in the field of ecology. Firstly, because in a renowned McGraw-Hill dictionary there appeared a notion that the Czochralski process was roughly equivalent to the term 'antropopression', well known in ecology [9]. But until now, it has not been proved in a satisfactory way that he coined that term. Czochralski died in 1953 at the age of 68, up until the end of his life being constantly watched by the Polish secret police, following some denunciations by a few people, unfortunately those coming also from the circle of his university colleagues. Fortunately, none of which have ever been proved [2]. To sum up: Jan Czochralski contributed quite substantially to many aspects of, what we now call, applied physics and chemical technology as well as of materials science. For example, his theory of recrystallization, though being particularly (and first) proposed for Sn [10], deserves recognition. He also contributed much to interdisciplinary research. It is worth noting that formally since the year 1986 [2], a systematic revival of Czochralski's reputation can be observed, at least in Poland. After the political changes in Poland had come about (around 1990), one may observe a visible revalidation of Czochralski's work and a better reception of his well-spread life style, mostly that during World War II, when he had to decide on how to live between Polish and German, historically different, standpoints, and under the critical conditions of the War. For further reading see: www.unipress.waw.pl/emrs/ and http://www.ptwk.org.pl/ where some recent events organised in Poland have been chosen. References [2] P.E. Tomaszewski, "Jan Czochralski and his method", Institute of Low Temperature & Structural Research, P.A.S. and ATUT Publishing House, Wroc=aw-Kcynia, 2003, in Polish and English. [3] W. Von Mollendorff and J. Czochralski, Z. d. Deutsch. Ing. 57, 931; 1014 (1913), in German. [4] J. Czochralski, Z. Anorg. Allg. Chemie 144, 263 (1925), in German. [5] H.J. Scheel, J. Cryst. Growth 211, 1 (2000). [6] G.K. Teal and J.B. Little, Phys. Rev. 78, 647 (1950). [7] P.E. Tomaszewski, J. Cryst. Growth 236, 1 (2002). [8] J. Czochralski, Przeglpd G.rniczo-Hutniczy, 6 pp., printed by Edmund Mirek & Co. Publishing House, Sosnowiec (Poland), 1935, in Polish. [9] "McGraw-Hill Dictionary of Scientific and Technical Terms", 3rd Edition, p. 408; see also [2]. [10] J. Czochralski, Int. Z. Metallogr. 8, 1 (1916), in German. Most readers enjoy having a better understanding of physical phenomena in everyday life, and being able to explain them to the layman. This has some extra relevance in view of the upcoming World Year of Physics 2005. This "Physics in daily life…" column is aimed at doing just that. Since it will span a wide variety of phenomena, most of which are outside the research expertise of the author, he welcomes comments, additions or corrections, especially from readers who happen to be more familiar with the topic. email: Hermans@Physics.LeidenUniv.nl Copyright EPS and EDP Sciences, 2004 |
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