Abstract: A silicon wafer is held in an airtight chamber by a silicon wafer holder. The silicon wafer holder is cooled by a cooler. High purity nitric acid is stored in a storage container disposed in the airtight container. The storage container is heated by a heater, thereby producing nitric acid gas. The nitric acid gas is condensed on the surface of the silicon wafer so that a thin film is formed. Thus, the surface of the silicon wafer is rendered hydrophilic. Thereafter, high purity hydrofluoric acid is dropped on high purity nitric acid in the storage container by an acid dropper, thereby producing hydrofluoric acid gas. By introducing the hydrofluoric acid gas into the thin film formed on the surface of the silicon wafer, an etching is performed while maintaining the surface of the silicon wafer in a good condition.

Abstract: A signal adapter including a first circuit board adapted to process wired TV signal and telephone signal from a first coaxial cable; a first casing holding the first circuit board at its one side and having a plurality of connectors at its opposite side adapted to transmit processed signal from the first circuit board to end users; a first cover fastened to the first casing and covered over the first circuit board, having a main signal input port through which wired TV signal and telephone signal are transmitted from a coaxial cable to the first circuit board, and a main signal output port through which wired TV signal and telephone signal are transmitted from the first circuit board to a next signal adapter through a second coaxial cable; a second circuit board adapted to provide the necessary telephone signal working power supply to the first circuit board; a second casing extended from one side of the first casing and adapted to hold the second circuit board on the inside; and a second cover fastened to th

Abstract: A compound semiconductor epitaxial wafer added with nitrogen to provide a high luminous efficiency. Epitaxial layers are grown on a single crystalline substrate 4 made of gallium phosphide or gallium arsenide to form a compound semiconductor epitaxial wafer EW. The epitaxial layers include at least an nitrogen-added gallium phosphide arsenide mixed crystalline epitaxial layer having an n-type carrier concentration descending gradually toward the uppermost surface of the grown layer in a continuous or stepwise manner before p-type impurity is diffused, and contain an intermediate layer 83 with an n-type carrier concentration of 4.times.10.sup.14 /cm.sup.3 or more and less than 3.5.times.10.sup.15 /cm.sup.3, and a surface layer 84 having an n-type carrier concentration equals to or lower than that for the intermediate layer 83.

Abstract: It is judged whether or not the pivotal movement of gimbal suspension is in a locked state. When the gimbal suspension is judged to be in the locked state, an actuator is stopped, and an operator is informed of this state, whereby the actuator can be prevented from being damaged, and the operator can rapidly respond to the locked state. An angular velocity value detected by an angular velocity sensor is read out (S6); an angle value detected by a position sensor is read out (S7); the read-out value of detedted angular velocity is subracted from an amplified value of detected angle (S9); the value resulting from the subtraction is integrated with respect to time (S10); and it is judged whether or not the gimbal suspension is in a locked state (S11). If it is consequently judged that the gimbal suspension is in the locked state, the control system is stopped (S12), and an alarm LED is flickered (S13).