Search

The crystal growth process of an InAs-GaAs binary semiconductor by the Traveling Liquidus-Zone (TLZ) method is investigated under terrestrial gravitational conditions numerically and the effect of the angle between the crystal growth direction and the gravity direction on the crystal growth process is discussed. First, this new crystal growth technique is explained and then a numerical mode and calculation method of the growth of binary crystals are developed, by which the flow field in the solution, the temperature and concentration fields in both the solution and crystals, and the shape and movement of the crystal-solution interfaces are determined. Focused is, in particular, the effect of the crystal size and the inclination angle on the crystal growth process. It is found that 1) When the crystal size is 2 mm, convection is reduced and the concentration field is not seriously deformed as long as the inclination angle is less than 1 degree. The degree of supercooling is remarkably reduced compared to the case when crystals are grown in the horizontal direction; 2) When the crystal size is greater than 5 mm, convection is intensified and the concentration field is seriously deformed. The degree of supercooling is increased as the inclination angle increases. The above results show that growing single crystals under terrestrial gravitational conditions are very difficult if the crystal size is greater than 5 mm., 資料番号: AA0046981003, レポート番号: NASDA-TMR-030006E

The critical freezing rate for avoiding the constitutional supercooling in the crystal growth of In(x)Ga(1-x)As from its melt has been investigated quantitatively and it is found that the critical freezing rate is between 0.25 and 0.28 mm/h at a temperature gradient in the melt of 10 C/cm when the convection is suppressed. Since the critical freezing rate that is calculated by the criteria reported by Tiller et al. in the diffusion limited growth is 0.22 mm/h at 10 C/cm, it can be said that tolerance for the constitutional supercooling exists. When convection in the melt existed, the critical freezing rate for avoiding the constitutional supercooling was reduced below the Tiller's criteria. Local inhomogeneity in the melt caused by convection might increase the local constitutional supercooling even at lower growth rate. The quantitative study on the effect of convection for the constitutional supercooling in a semiconductor crystal growth is the first time., 資料番号: AA0046981002, レポート番号: NASDA-TMR-030006E

第28回宇宙利用シンポジウム (2012年1月23-24日. 日本学術会議), 港区, 東京都, Space Utilization Research (January 23-24, 2012. Science Council of Japan), Minato-ku, Tokyo Japan, 資料番号: SA6000032022, レポート番号: M22

Total of four SiGe crystal growth experiments aboard the ISS were successfully performed for evaluating a two-dimensional growth model of the traveling liquidus zone (TLZ) method and for obtaining insights into large homogeneous SiGe crystal growth conditions. The TLZ growth requires diffusion limited mass transport in a melt and experiments in microgravity are essential. Although a little deviation from the expected compositional uniformity due to emissivity change of the cartridge surface is observed, homogeneous SiGe crystals are grown. Over all axial growth rate is consistent with the one-dimensional TLZ growth model prediction. However, radial growth rates are different from the two-dimensional growth model prediction. The difference is closely related to the flat interface shape in space grown crystals compared with the terrestrial ones and the radial compositional uniformity is much better than those of terrestrially grown crystals. Suppression of convection in a melt is favorable for obtaining flat freezing interface and is beneficial to large homogeneous SiGe crystal growth. It is expected that the obtained results are utilized and large homogeneous crystal growth is realized on the ground and electronic devices using SiGe substrates are developed., 形態: カラー図版あり, Physical characteristics: Original contains color illustrations, 資料番号: DS1640101000

第29回宇宙環境利用シンポジウム (2015年1月24日-25日. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS)), 相模原市, 神奈川県, Space Utilization Research (January 24-25, 2015. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency(JAXA)(ISAS)), Sagamihara, Kanagawa Japan, 資料番号: SA6000035020, レポート番号: ISAS-SUR29-S15

We have succeeded in growing large and high quality platy In(x)Ga(1-x)As (x: 0.1-0.13) single crystals by the Traveling Liquidus-Zone (TLZ) method. Among factors which affect crystal quality, the most influential factor is temperature stability at the growth region when the composition of grown crystals is in the range between In(0.1)Ga(0.9)As and In(0.13)Ga(0.87)As; when the temperature stability was better than +/- 0.1 C, compositional uniformity was 0.13 with sigma of 0.001 where sigma is the standard deviation, and 0.13 with sigma of 0.006 when the temperature stability was +/- 0.2 C. The appropriate temperatures at the feed region were between 1,170 and 1,180 C. Temperature gradient also affected crystal quality through the variation of growth rate. Temperature gradients chosen for high quality crystal growth were in the range between 25 and 28 C/cm, which were measured outside of quartz ampoules. Finally, In(0.13)Ga(0.87)As single crystals having high quality area larger than 10 x 30 sq mm were reproducibly grown. Such large and high quality bulk single crystals which can be used as substrates of laser diodes operating at the wavelength of 1.3 micrometers were grown for the first time., 資料番号: AA0063221000, レポート番号: JAXA-RR-06-014E

化合物半導体InGaAs結晶成長を行うことを想定し、TLZ法における数値シミュレーションを行い、以下の項目について解析をした。1)地上重力場での結晶成長解析(結晶径20mm)、2)微小重力場での結晶成長解析(結晶径20mm)、3)地上重力場での結晶成長解析(結晶径10mm)、4)微小重力場での結晶成長解析(結晶径10mm)。, Crystal growth simulations of a binary InAs-GaAs semiconductor were carried out. The following problems were investigated; 1) Development of an advanced simulation code for the analysis of the velocity, temperature, concentration fields and interfacial shapes by TLZ method and 2) Analysis of the crystal growth process under terrestrial gravity and microgravity conditions., 資料番号: AA0046955000, レポート番号: JAXA-CR-03-001

今期は、1)平均組成x=0.3〜0.4の傾斜組成分布を持つ長さ150mmの組成的過冷却のない傾斜組成多結晶原料を3本製作した。この原料から組成分布をRaman散乱により非破壊で測定し一端のIn組成が0.8以上になるように試料を切り出した。試料形状は直径10mm、長さ100mmである。これらの試料をTLZ法による成長実験に使用した。2)TLZ法による結晶成長実験条件の検討はまずるつぼ材質や形状などの実験条件を宇宙開発事業団条件と一致させた。成長領域での温度勾配を40/cm以上にしかつTLZが可能な温度分布を実現するため、温度分布測定を実施した。その結果に基づいてTLZ法による成長実験を実施した。単結晶化は実現していないが得られた組成分布などの検討を進めている。3)単結晶が得られていないため結晶特性の評価は十分ではないが、Raman散乱や組織観察は実施。4)成長条件決定に必要なデータを取るため10mm径および2mm径の試料について3度の急冷実験を実施した。, The following researches have been carried out in order to make source materials for the TLZ-experiments, of which purpose is growth of InGaAs single crystal having uniform composition and in order to obtain the suitable experimental conditions for TLZ growth method. 1) The 3 polycrystalline source materials having average composition of x = 0.3 to 0.4 were prepared by a directional solidification method. Several starting materials for TLZ experiments were cut from the source materials, of which compositions were nondestructively measured by Raman scattering method. The diameter is 10 mm and the length is 100 mm. 2) For the TLZ experiment same experimental system and conditions as the NASDA's one were made except higher temperature gradient of 40 C/cm. Precise temperature profile measurement has been carried out. On the basis of the results the several TLZ growths were carried out. Single crystal has not been obtained yet but the composition profiles and Raman scattering were examined. 3) In order to obtain the necessary information for crystal growth, three quench experiments were carried out in the sample with 2 and 10 mm diameter., 資料番号: AA0046956000, レポート番号: JAXA-CR-03-002E

資料番号: AA0046981000, レポート番号: NASDA-TMR-030006E

第27回宇宙利用シンポジウム (2011年1月24日-25日, 宇宙航空研究開発機構宇宙科学研究所相模原キャンパス), 相模原市, 神奈川県, The Twenty-seventh Space Utilization Symposium (January 24-25, 2011. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)), Sagamihara, Kanagawa Japan, We have prepared for SiGe crystal growth experiments on board the ISS "Kibo". The two-dimensional model of the TLZ (traveling liquidus-zone) method will be studied by microgravity experiments because disturbance in constituent element by convection upon freezing is avoided in microgravity. For successful space experiments, growth conditions using a bread board model of a gradient heating furnace (GHF) for space experiments are examined on the ground. Procedures for determining growth conditions and finally fixed growth conditions are reported., 著者人数: 15人, 形態: カラー図版あり, Number of authors: 15, Physical characteristics: Original contains color illustrations, 資料番号: AA0065129016

We are preparing for crystal growth experiments in microgravity using a Gradient Heating Furnace (GHF). The one-dimensional Traveling Liquidus-Zone (TLZ) growth model is limited by the radial temperature gradient, convection in a melt and so on. Such factors affecting one-dimensionality are studied experimentally and theoretically. From a viewpoint of single crystal growth we would like to select Si-Ge as target materials. Here, achievements in the present preparatory stage are reported., 資料番号: AA0063706003