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Aging-free InP substrates ready for molecular beam epitaxy have been developed by the inert gas packaging technique. The surface degradation of the InP substrate after chemical cleaning was evaluated by the quality of the 2DEG heterostructure grown on the substrate. The InP substrate in a package filled with nitrogen gas was used for MBE growth. The Hall mobility of an InAlAs/InGaAs heterostructure directly grown on the InP substrate without any pretreatment or chemical etching is larger than 10 000 cm2 /V s at 300 K. There are no aging effects on the sample stored even after six months.

Synopsis : In rolling of ultra thin stainless steel foil, there are two rolling limits. One is owing to elastic deformation of work rolls, and the other is owing to edge crack of rolled foil. In this paper, fundamental investigation was conducted about the basic characteristic of the rolling limits of ultra thin stainless steel foil. The influence of several rolling conditions on minimum thickness and behavior of edge crack were investigated experimentally. This paper provides new formula to predict the minimum thickness in ultra thin foil rolling. The relation between the edge crack depth and the rolling conditions is also discussed. The edge crack expands with rolling passes. However, the degree of the edge crack at same foil thickness shows different behavior depending on rolling conditions. The depth of edge crack rolled by small diameter work rolls is shallower than that of same thickness foil rolled by large diameter work rolls. Moreover, when Young's modulus of work rolls is high, it turns out that the edge crack is small. Based on detailed observation of the foil edge phenomenon, good correlation between edge crack depth and foil thickness at extreme edge portion is found. From those experimental results, it is suggested that the rolling conditions advantageous to control edge drop are effective to suppress edge crack expansion.

In rolling of ultra thin stainless steel foil, there are two rolling limits. One is owing to elastic deformation of work rolls, and the other is owing to edge crack of rolled foil. In this paper, fundamental investigation was conducted about the basic characteristic of the rolling limits of ultra thin stainless steel foil. The influence of several rolling conditions on minimum thickness and behavior of edge crack were investigated experimentally. This paper provides new formula to predict the minimum thickness in ultra thin foil rolling. The relation between the edge crack depth and the rolling conditions is also discussed. The edge crack expands with rolling passes. However, the degree of the edge crack at same foil thickness shows different behavior depending on rolling conditions. The depth of edge crack rolled by small diameter work rolls is shallower than that of same thickness foil rolled by large diameter work rolls. Moreover, when Young's modulus of work rolls is high, it turns out that the edge crack is small. Based on detailed observation of the foil edge phenomenon, good correlation between edge crack depth and foil thickness at extreme edge portion is found. From those experimental results, it is suggested that the rolling conditions advantageous to control edge drop are effective to suppress edge crack expansion.