After the Second World War academic life as education and research had to be re-established as well as industrial production had to be reinstalled in Germany. This happened separately in the eastern and the western part, that is, in the German Democratic Republic (GDR) and in the Federal Republic of Germany (FRG) where both parts have had a very successful development. Here, we will describe only the most important steps because the main focus of the article is on the development of the societies representing crystal growth in GDR (second section) in FRG (third section), and in unified Germany. Despite all the restrictions, several attempts have been made from both sides to overcome this separation at least for certain events. After the wall opened in 1989 the situation was quickly changed. Crystal growers from east and west came together. In the end the colleagues from the east part joined the Deutsche Gesellschaft für Kristallwachstum und Kristallzüchtung (DGKK) which became the family for all German crystal growers. Details will be given in the fourth section of this article. A major player in re-establishing academic life was Max Volmer, who became the president of the German Academy of Science in 1955. In the nineteen twenties he established the fundamentals of phase transitions and nucleation theory together with other researchers. Now, besides the more general tasks he supported the continuation of this research direction. In order to re-establish education, research, and industry one plant of the industrial crystal growth for optical applications has been established in Jena at VEB Carl Zeiss. There, main contributions were provided for the development of the Kyropoulos process of NaCl, KBr, and LiF as well as the Bridgman–Stockbarger method of CaF2 and KRS-5 (Tl(Br,J), for infrared) crystals. The crystals were used for optics and lenses. In Bitterfeld the Verneuil Method was used for the production of gemstones. Since 1957 industrial growth was performed also in Freiberg/Saxony at “VEB Spurenmetalle Freiberg,” SMF. Since the sixties Ge single crystals and later Si crystals (4″ FZ-Si and 6″ Cz Si) were grown for electronic applications. Since 1970 also research on III-V-compounds started and the production followed 1982. Considering fundamental research, pioneering work was done by Will Kleber at the Mineralogisch-Petrographisches Institut of the Humboldt University of Berlin. His investigations on crystallization speed in undercooled melts (1955) became very famous. Another main player in the field of fundamental research was Heinz Bethge at the University of Halle, the location for electron microscopy of the German Academy of Science. In 1954 he succeeded together with O. Schaffer in obtaining the first pictures of evaporated spiral steps at the penetration point of screw dislocations by electron microscopy. Furthermore, Heinz Bethge was one of the founders of the International Organization for Crystal Growth (IOCG) in 1966. He held a personal membership in the council of IOCG until 1983. In 1963 the subcommision “Kristallzüchtung” (crystal growth) within the German Academy of Science was founded. The first president was Will Kleber. Klaus–Thomas Wilke became the secretary. Both are still well known because of their fundamental books on crystallography and crystal growth. On 23rd April 1965 the “Vereinigung für Kristallographie (VfK)” (Association for Crystallography) was founded in East-Berlin as a group within the “Gesellschaft für Geologische Wissenschaften der DDR” (Society for Geological Sciences of GDR). Hermann Neels was the first VFK president which later also initiated the foundation of the working group “Kristallisation” within VfK, quasi as continuation of the former subcommission “Kristallzüchtung.” This was 1971 and in November of that year the first VfK conference on single crystalline materials was held (the framework was “Semiconductor Crystallography”). During the following years this group was first led by Manfred Jurisch (Dresden) and later by Günther Kühn (Leipzig). At that time key crystal growth activities were developed under the explicit support of the VFK presidents Manfred Schenk (Dresden and Berlin), Hans-Joachim Bautsch (Berlin), Peter Paufler (Leipzig, acting after the unification of Germany as the president of the German Association for Crystallography in 2000–2003) and Ursula Steinike (Berlin). VFK conferences on crystallization were organized in the years 1973, 1975, 1978, 1984, and 1989 as well as about 40 round table discussions were arranged. Very important was the organization of winter schools under the guidance of Manfred Jurisch (Dresden). The first one took place in 1977 and from that time on every three years (see Figure 1). About 100 participants attended these schools, which contributed a lot to establish a broad knowledge of the fundamentals and current developments in crystal growth. It should be noted that during these times the access to certain progress and knowledge was very limited because of the severe travel restrictions in GDR. However, there were contacts for instance between the growers of the Technikum für Kristallzüchtung (at the “Zentrum für wissenschaftlichen Gerätebau” of the GDR Academy of Science) and the development department of Wacker Chemitronic as well to those at the Jülich Research Centre. A contact to the colleagues of the East Bloc was generally not a problem but a participation at an international conference outside this bloc was much more complicated. One action of the working group was the organization of seminars about dedicated international conferences. Typically, a small group of people had the permission to travel abroad to an international conference. Afterward, they were invited to those seminars to give detailed reports on the scientific developments presented at the conference. The other initiative was to invite speakers from FRG and other West-European countries to conferences in GDR. For instance, in 1973 D. D. Double from Oxford (GB) gave a talk about the solidification of eutectic systems on the VfK conference. At the conference five years later Siegfried Haussühl (University Köln) spoke about the systematic search for single crystals with strong polarities. He was the first speaker of DGKK at such a conference. Worth mentioning at this point are the summer schools for crystal growth of the “Council for Mutual Economic Assistance (COMECON)”. These schools took place in Bulgaria and were chaired by Rotislaw Kaichev (Sofia) and Alexander Chernov (Moscow) and the working group supported always the participation of young researches of GDR. The general political situation has changed in February 1989 essentially initiated by Gorbatschow's politics of Perestroika. At the 23rd annual conference of VfK in Leipzig many speakers from western countries could be invited. From DGKK Klaus–Werner Benz (Freiburg), Elisabeth Bauser (Stuttgart), and Georg Müller (Erlangen) participated. Also from other Western European countries crystal growers came to Leipzig, as, for example, Raymond Kern (France), L. John Giling (The Netherlands), Roberto Fornari (Italy). Later in this year at the ICCG-9 in Sendai the “Crystal Growth Section of the Association of Crystallography – CGS/VfK” became a regular member of IOCG. This section was an integration of working groups “crystallization,” “industrial crystallization,” and “interfaces and thin layers.” The then president and secretary of the National Committee for Crystallography, Hermann Neels and Peter Rudolph, contributed very actively to the establishment of the section in the International Organization. Fast development of crystal growth in industry started during the fifties. The Philips Research Laboratory in Hamburg–Stellingen, founded 1957, was famous for ferri-magnetic materials with garnet structure and epitaxial layers for magnetic, magneto-optical, and detector applications. But also high melting oxides up to 1800 °C were grown from the melt by the Czochralski method (DGKK-Mitteilungsblatt Nr. 40, 1984). The crystal growth activities ended in 1990 when the research laboratory in Hamburg was closed. Another significant material group with crucial single crystal importance concerns the semiconductors. Directly after the Second World War the Siemens Cooperation started in Erlangen to develop semiconductor materials, like germanium, silicon, and compound semiconductors. The branch was headed by Eberhard Spenke and Walter Schottky. 1951 Heinrich Welker started his famous investigations of the III-V-semiconductors (for more details see the chapter of Jochen Friedrich and Georg Müller). In 1953 the research on high-purity silicon started in Burghausen followed by the semi-conductor production 1958. One year later the floating zone process was established. Then, in 1968 Wacker-Chemitronic GmbH was founded, which was renamed in 1994 into Wacker Siltronic GmbH. Now it is a stock company (Siltronic AG). The company was always engaged in the growth of electronic materials, namely silicon, InP, and GaAs. After the unification of Germany the growth of III-V compounds was moved to Freiberger Compound Material GmbH (FCM), whereas Siltronic GmbH was focusing on silicon. In addition to the traditional plant in Burghausen (Bavaria) Siltronic established a new branch for production of 12-inch (300 mm) silicon in Freiberg (2004). Today, both FCM and Siltronic are world-leading companies. Historically, at the beginning of sixties crystal growers were spread over many of the established societies acting there in sections and subgroups. Just to name some of them here: Deutsche Mineralogische Gesellschaft (DMG), Gesellschaft Deutscher Chemiker (GDCH), Deutsche Physikalische Gesellschaft (DPG), Bunsengesellschaft, Verein Deutscher Ingenieure (VDI). The crystal growers form a new section in one of the existing societies as, for example, DMG, DPG, GDCH, VDI. The crystal growers found a new and own society, for example, “Gesellschaft for Kristallzüchtung und Kristallisation” In spring 1969 a questionnaire was distributed among the people in this field. One third (of 150) voted for an own society. Most of the active crystal growers were in this group. The rest preferred a docking to one of the established societies. Founding an own group within the section “Kristallkunde” of DMG. Founding a free association of researchers Founding an own society with the option to be included in a German Society for Crystallography. A German Society for Crystallography did not exist during that time and the option was just for the case that such society would be founded. Several further discussions among the relevant persons led finally to the conclusion that the third option would be the best. On 9th July 1970 the meeting of the “Ausschuss Kristallisation” (committee crystallization) of the Verfahrenstechnischen Gesellschaft (VTG) within VDI took place in Bensheim-Auerbach, in which many crystal growers participated. That very evening a part of them met for the founding assembly of DGKK. In total of 13 members founded the Deutsche Gesellschaft für Kristallwachstum und Kristallzüchtung (German Association for Crystal Growth) as listed in Figure 2. The name of the association includes a peculiarity of the German language. There is the word Kristallwachstum for fundamental aspects of crystal growth and the one Kristallzüchtung for the growth of crystals. Siegfried Haussühl was elected as president and Rudolf Nitsche as his deputy. All former presidents and the present one are listed in Table 1. The Board of DGKK was firstly presented by photo in the second journal edition of the “Mitteilungsblatt” in 1983 (see Figure 3). The first general assembly took place in conjunction with the colloquium “Crystal Growth” of the German Research Foundation (DFG) in München on 15th October 1970. The membership had been increased to 73 personal members and three legal entities. Additional 13 persons joined DGKK during the colloquium. At this point it is worth mentioning that four years before the International Organization for Crystal Growth (IOCG) was founded by Michael Schieber. He noticed that such an International Organization would be much powerful with the support of national societies. Thus, in 1971 in total ten national societies became member of IOCG, besides those from France, Israel, Italy, Japan, The Netherlands, Spain, Switzerland, UK, USA also DGKK from Germany. Michael Schieber did not only found IOCG but also initiate the first International Conference on Crystal Growth (ICCG-1), which was held in June 1966 in Boston with a great success (625 participants). From that on ICCG was an important and prestigious event. In 1977 Kurt Recker proposed as the president of DGKK the German town Stuttgart for ICCG-7. The proposal was successful and 1983 Germany was the host for this international event. Another activity on national level was establishing an exhibition on crystal growth in the “Deutsches Museum” in München. Already in 1971 the board of DGKK fostered a small exhibition and the result was a showcase with single crystals, donated by members of DGKK. During reconstruction of the museum the objects were removed and suffered from water damage. The next attempt of DGKK was made in 1983. The museum planned to arrange an exhibition on mathematical instruments, computers, and micro-electronics. With the help on major donations from various companies and members of DGKK one room could be created with various objects from crystal growth. The new rooms were opened in May 1988. In the meantime, the museum has been rearranged again and the former exhibitions—also the one on crystal growth—were replaced by new ones based on modern concepts. Another direction of the DGKK activities is shown by the following: in the general assembly held 1986 in Erlangen Helmut Wenzl proposed to organize a bilateral Summer School with the colleagues in GDR. In particular, he made the suggestion to organize a school on “Epitaxy of Semiconductor Compounds” in Dresden in September 1987 (Minutes of the general assembly 1986). This would intensify the relations in a new way. He mentioned that BMFT (German Ministry for Research and Technology) would welcome this initiative. Rudolf Nitsche had already had some discussion with representatives in the GDR. Unfortunately, this idea was never realized. However, it shows the engagement for joint activities of east and west during that time. The first German Crystal Growth Conference after the fall of the wall took place in Frankfurt (Main) in March 1990. A large number of scientists from GDR attended this conference. Many also became a member of DGKK already in Frankfurt or shortly afterward. This was officially recognized during the general assembly during the next conference, 1991 in Gießen. During this time of dramatic changes Helmut Wenzl was the president of DGKK (1990–1993). His great personality enabled the successful integration of the crystal growers from the group “Kristallisation” of VfK. This was one reason that the working group, Kristallisation“ of VfK became obsolete. The other one was that the VfK founded together with the “Arbeitsgemeinschaft Kristallographie” (AGKr) the new society “Deutsche Gesellschaft für Kristallographie” (DGK) on 12th March 1991. From that time on we had DGK and DGKK presenting crystallography and crystal growth in Germany, respectively. Worth mentioning at this point is the journal “Mitteilungsblatt,” which has been published twice a year since 1983 (before it was a newsletter). During that time it had a section “Kristallzüchtung in Deutschland” (Crystal Growth in Germany). It was regarded as a good platform to present the locations of crystal growth in east and west. In parallel a number of new developments started in industry. The most important event after the German unification may be the foundation of Freiberger Electronic Werkstoffe GmbH, FEW in Freiberg out of the former “Spurenmetalle Freiberg”, SMF in 1990 and the transfer of the GaAs production (LEC) from Siltronic to FEW in 1991. Four years later the activities on III-V-compounds was transferred to the newly founded Freiberger Compound Materials GmbH (FCM) and FEW was integrated into Siltronic. Since that time a remarkable increase of quality in the growth of III-V-compounds was achieved by improvement of the Vertical Gradient Freeze method. In Idar–Oberstein, the research institute “Forschungsinstitut für mineralische und metallische Werkstoffe GmbH, FEE” was founded for the research and growth of single crystals based on Y-Al-Garnets (YAG) for laser or other (electro-)optical applications in 1990. Since 2018 it has been a part of the US-American company Electro-Optics Technology (EOT) (Mitteilungsblatt Nr. 68, 1998). For high-power electronic applications SiC has become a more and more important material. In Germany it is the SiCrystal GmbH in Nürnberg, which grows the SiC crystals up to 150 mm from the vapor phase. It was founded 1996 from outsourcing the SiC growth from the University of Erlangen. Huge but short activities happened in photovoltaics, mainly the growth of silicon, RWE Schott Solar GmbH, Deutsche Solar GmbH, or Solar World GmbH as well as of CuIn2S4 by Würth Solar GmbH & Co. KG, Schwäbisch Hall until the crash of photovoltaic business around 2010 finished most of the companies in Germany. Another branch of crystal growth was filled by Schott Lithotec AG (starting 1998 as a subsidiary of Schott Glas in Mainz, now in Jena): huge CaF2 crystals up to 100 kg within 8 weeks for stepper lenses and other optical devices were grown. Since 1976 IR technology is hosted in Heilbronn, initially by AEG-Telefunken, later by the outsourced company AIM Infrared Module GmbH (1996). For this kind of modules, crystals and epitaxial layers of II-V–compounds, such as (Cd,Zn)Te and (Hg,Cd)Te are produced. Last but not least large high-quality Ge crystals are manufactured at Photonic Sense GmbH in Eisenach. An important date for crystal growth research in Germany was 1st January 1992 when the Institute for Crystal Growth (IKZ) was founded in Berlin Adlershof, based on the former GDR institutes “Technikum für Kristallzüchtung” of the former, Zentrums für wissenschaftlichen Gerätebau (ZWG)” of the Akademie der Wissenschaften” together with the groups for crystal growth of II-VI-compounds of the “Zentralinstituts der Elektronenphysik (ZIE)” and the groups for oxide crystals of the “Zentralinstituts für Optik und Spektroskopie (ZOS).” Winfried Schröder became the director of the institute and in 1994 the first DGKK president from the east part of Germany. As a member of the Leibniz Society the institute included the term “Leibniz” 2008 into the name and is “Leibniz-Institut für Kristallzüchtung” today. It is one of the leading institutes for crystal growth in Europe and worldwide. Despite the fact that research in crystal growth is reduced at many academic places there is still a reasonable number of students and young researchers in the field of crystal growth. In order to be better presented they organized themselves as ”young DGKK” (jDGKK) in 2012. They organize every year a symposium a day before the annual conference of DGKK and 2019 the 1st joint meeting together with the “young crystallographers” (jDGK), was organized in Köln. The Annual Conference on crystal growth is as old as the association itself. The first conference was organized at the University of Bonn in 1971. Since that time the conference on crystal growth has been held every year—sometimes in conjunction with the European or International conference. The list of all conferences is shown in Table 2. Often the conference was organized with other societies in Germany as Arbeitsgemeinschaft für Kristallographie (AGKr), later the Deutsche Gesellschaft für Kristallographie (DGK), Deutsche Physikalische Gesellschaft (DPG) or in the neighboring countries like Assoziazione Italiano di Crescita dei Cristalli (AICC), British Association for Crystal Growth (BACG), The Czecheslowak Association for Crystal Growth (CSACG), Group Français de Croissance Cristalline (GFCC), Kontaktgroep Kristalgroei Nederland (KKN), Polish Society for Crystal Growth (PSCG), and Section Crystal Growth of Swiss Society for Crystallography (SKW). Already the founders of DGKK were aware of the importance of an annual conference for exchanging results and ideas. They put the task of ensuring the organization of the conference every year as an obligatory task for the council into the by-law. Such a conference was also an excellent opportunity to meet with colleagues from the neighboring countries and many joint conferences were organized during the years. GaAs and other III-V compounds CdTe (II-VI compounds) Oxides Epitaxy of semiconductors Support of young researchers They should be seen as a seed for establish working groups when successful. In November 1986 a symposium on epitaxy was held in Stuttgart at Standard Elektrik Lorenz AG (SEL) organized by Peter Speier with in total 30 participants. Twice, in March 1987 and October 1987 symposia on III-V compounds took place at Siemens AG in Erlangen. For these two events with about 60 participants Georg Müller was responsible. Thus, two working groups were established, which have been acting very successful until today. Epitaxy of semiconductors was later restricted to epitaxy of III-V compounds but nevertheless the meetings are the largest among all working groups (about 100 participants). The working group on GaAs and other III-V compounds were dominated in the nineties by the development of industrial processes for GaAs and also InP single crystals. Characterization and their methods played a significant role for understanding the defects, which was a prerequisite for improving the crystal quality. In the years 2000 SiC, GaN, and also AlN emerged to become important materials for power and opto-electronics and were included. At the end of the 2000s there was this hype in the PV market and many growers moved to multi-crystalline or mono silicon for PV applications. Therefore, the topics were extended by this subject. The first meeting on II-VI compounds took place in 1986 in Würzburg with 25 participants followed by another one in March 1988 at University Karlsruhe. At that time German Müller–Vogt was responsible for this working group. It appeared that thin layers of II-VI compounds became more and more important and not many researchers in Germany worked on bulk crystal growth. There were a lot of activities also by other communities, for example, a priority programme was established by the German Science Foundation, a European Workshop on II-VI semiconductors was organized regularly. Therefore, extra activities by DGKK were not necessary. On the contrary, the topic of oxide crystals, especially for lasers and non-linear optics, is today as important as it was at the end of the eighties. The first symposium was organized 1987 at the University Osnabrück. Three years later the working group “oxides” was founded at the general assembly in Frankfurt/Main 1990. Major players were Wolfgang Tolksdorf from Philips in Hamburg, Hans-Josef Paus in Stuttgart (who got part of the growth equipment from Philips in 1990) and Lothar Ackermann from FEE Idar–Oberstein. Already colleagues from the former GDR joined the group mainly from the former “Zentralinsitut für Optik und Spektroskopie” (ZOS) and Carl Zeiss (Jena). The first meeting was organized by Hans-Josef Paus at the Institute of Physics at the University Stuttgart. The portfolio of materials for laser and non-linear optics was very broad. Such kind of materials have been also investigated in France and consequently Lothar Ackermann proposed to invite also colleagues from France. Since that time the workshop is organized alternating in Germany and France. A more fundamental subject is growth kinetics. It has been noticed that there were many activities in the Netherlands in this field but it was not clear, which work was done in Germany. The researchers in this field were spread over different places and disciplines, and only a few were member of DGKK at that time. Therefore, a workshop on this topic was organized in 2000 by Peter Rudolph. It appeared that indeed there was a lot of interesting research in this field going in Germany. From dendritic growth to step bunching in epitaxy, from real-time observations of eutectic solidification to multi-scale simulations of epitaxial growth, there was broad spectrum of contributions by experts from an interdisciplinary environment. On the contrary, there are also topics closely related to industrial crystal growth. Therefore, in 2013 a new working group was founded by Albrecht Seidl (Industrial Crystal Growth). The idea was to address more general topics relevant to industrial processes of crystal growth rather than to deal with particular growth processes or brand new results. The first edition was on high-temperature materials for crystal growth. Another focused on the important subject how to measure during the industrial growth process and how to control. The success of these workshops showed that there are still many companies in Germany, which are active in this field. With increasing computer power during the nineties numerical calculations of the growth process became feasible and thus an emerging topic of research and development. Consequently, a new working group was created by Albrecht Seidl in 2000: “Applied Numerical Simulation.” It is worth mentioning that the initiative came from researchers in industry. It was of great interest for the companies active in crystal growth to learn what could be computed and how could this improve the process development. The workshops were attended by engineers and crystal growers from industry, experimental researchers, researchers doing simulation, and mathematicians. It was the time of developing codes with sufficient stability and flexibility but also with an easy-to-use interface. After twelve years the main development was completed and using numerical calculations for process development has become a standard. There are still challenges, especially with emerging topics like artificial intelligence but this requires a different character of the workshop. Today, in the thirtieth year after the “Wall was broken,” the DGKK is a beautiful, unified, very active, and internationally highly respected association joining about 400 members from whole Germany and even abroad working in the fields of crystal growth, preparation, epitaxy, and analysis. Figure 4 shows a large DGKK delegation at the ICCGE-16 in Beijing 2010.