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A high-speed heterojunction bipolar transistor in a large injection of electrons from the emitter and a method for production thereof. In a typical example of the SiGeC heterojunction bipolar transistor, the collector has a layer of n-type single-crystal Si and a layer of n-type single-crystal SiGe,

A high-speed heterojunction bipolar transistor in a large injection of electrons from the emitter and a method for production thereof. In a typical example of the SiGeC heterojunction bipolar transistor, the collector has a layer of n-type single-crystal Si and a layer of n-type single-crystal SiGe, the base is a layer of heavily doped p-type single-crystal SiGeC, and the emitter is a layer of n-type single-crystal Si. At the heterointerface between the layer of n-type single-crystal SiGe and the layer of p-type single-crystal SiGeC, the bandgap of the p-type single-crystal SiGeC is larger than that of the layer of n-type single-crystal SiGe. Even though the effective neutral base expands due to an increase in electrons injected from the emitter, no energy barrier occurs in the conduction band at the heterointerface between the layer of n-type single-crystal SiGe and the layer of p-type single-crystal SiGeC. Thus, the diffusion of electrons is not inhibited and it is possible to realize high-speed heterojunction bipolar transistors even in the high injection state.

대표청구항 ▼

A high-speed heterojunction bipolar transistor in a large injection of electrons from the emitter and a method for production thereof. In a typical example of the SiGeC heterojunction bipolar transistor, the collector has a layer of n-type single-crystal Si and a layer of n-type single-crystal SiGe,

A high-speed heterojunction bipolar transistor in a large injection of electrons from the emitter and a method for production thereof. In a typical example of the SiGeC heterojunction bipolar transistor, the collector has a layer of n-type single-crystal Si and a layer of n-type single-crystal SiGe, the base is a layer of heavily doped p-type single-crystal SiGeC, and the emitter is a layer of n-type single-crystal Si. At the heterointerface between the layer of n-type single-crystal SiGe and the layer of p-type single-crystal SiGeC, the bandgap of the p-type single-crystal SiGeC is larger than that of the layer of n-type single-crystal SiGe. Even though the effective neutral base expands due to an increase in electrons injected from the emitter, no energy barrier occurs in the conduction band at the heterointerface between the layer of n-type single-crystal SiGe and the layer of p-type single-crystal SiGeC. Thus, the diffusion of electrons is not inhibited and it is possible to realize high-speed heterojunction bipolar transistors even in the high injection state. l image signal is corrected by being divided by the signal component representing the cell partition walls, wherein said signal component is a sampling time. 8. A radiation image acquisition method according to claim 1, wherein a mirror surface that raises the reflective-index of the cell partition walls, with respect to the stimulating light, is formed on the upper surface of said cell partition walls. 9. A radiation image acquisition method according to claim 8, wherein the digital image signal is corrected by being divided by the signal component representing the cell partition walls, wherein said signal component is a sampling time. 10. A radiation image acquisition method according to claim 1, wherein the cell partition walls are tinted so that the reflective index of said cell partition walls is decreased with respect to the stimulating light. 11. A radiation image acquisition method according to claim 10, wherein the digital image signal is corrected by being divided by the signal component representing the cell partition walls, wherein said signal component is a sampling time. 12. A method of obtaining a radiation image, comprising: scanning a phosphor layer formed of a plurality of cells, each of said cells bounded by a plurality of partition walls, said plurality of cells arranged in at least a main scanning direction, filled with stimulable phosphor and bearing thereon a radiation image in said main and a sub-scanning directions with a stimulating light; photoelectrically detecting as an analog image signal the stimulated emission emitted by the phosphor layer due to said scanning; and digitizing said analog image signal to obtain a digital image signal representing the radiation image, wherein a signal component representing one of a plurality of partition walls of said cells included in the analog image signal is recognized, and the digital image signal is obtained from the component of the analog signal obtained between said recognized signal components representing the partition walls, and wherein the detected signal component representing the partition walls is used as a trigger signal in digitizing the analog image signal to obtain the digital image signal. 13. A method of obtaining a radiation image, comprising: forming on the upper surface of a plurality of cell partition walls that bound a plurality of cells in a phosphor layer a mirror surface that raises the reflective-index of the cell partition walls with respect to the stimulating light; scanning said phosphor layer, said phosphor layer formed of said a plurality of cells, said plurality of cells arranged in at least a main scanning direction, filled with stimulable phosphor and bearing thereon a radiation image in said main and a sub-scanning directions with a stimulating light; photoelectrically detecting as an analog image signal the stimulated emission emitted by the phosphor layer due to said scanning; digitizing said analog image signal to obtain a digital image signal representing the radiation image, wherein a signal component representing one of a plurality of partition walls of said cells included in the analog image signal is recognized, and the digital image signal is obtained from the component of the analog signal obtained between said recognized signal components representing the partition walls, wherein the detected signal component representing the partition walls is used as a trigger signal in digitizing the analog image signal to obtain the digital image signal. 14. A method of detecting the interval between cells comprising scanning a phosphor layer formed of a plurality of cells, each cell bounded by a plurality of partition walls, said plurality of cells arranged in at least a main scanning direction, filled with stimulable phosphor and bearing thereon a radiation image in said main and a sub-scanning directions with a stimulating light, photoelectrically detecting as an analog image signal a stimulated emission e mitted by the phosphor layer due to said scanning, and digitizing said analog image signal to obtain a digital image signal representing the radiation image, wherein a signal component representing the partition walls included in the analog signal is recognized, and based on said recognized signal component representing the partition walls, the space interval between cells is obtained. 15. A method of detecting the interval between cells as defined in claim 14 further comprising the steps of mixing a phosphor having light conversion characteristics different from the stimulable phosphor with either the cell partition walls or the stimulable phosphor contained therebetween, detecting fluorescent light emitted from the phosphor material in the phosphor layer due to aforementioned scanning, recognizing the signal component representing the partition walls included in the signal of the detected fluorescent light, and based on said recognized signal component representing the partition walls, obtaining the interval between cells. 16. A method of detecting the interval between cells as defined in claim 15, wherein the recognized signal component representing the partition walls is used as a trigger signal in digitizing the analog image signal to obtain the digital image signal. 17. A method of detecting the interval between cells as defined in claim 14 further comprising the steps of detecting the reflected stimulated light reflected by the phosphor layer due to said scanning, recognizing the signal component representing the partition walls included in the signal obtained by detecting said reflected stimulating light, and based on said recognized signal component representing the partition walls, obtaining the interval between cells. 18. A radiation image acquisition apparatus comprising a phosphor layer formed of a plurality of cells, each cell bounded by a plurality of partition walls, said plurality of cells arranged in at least a main scanning direction, filled with stimulable phosphor and bearing thereon a radiation image, a scanning apparatus that scans the phosphor layer in the main and a sub-scanning directions with a stimulating light, a detection means that photoelectrically detects as an analog image signal a stimulated emission from the phosphor layer caused by the scanning, a signal acquisition means that digitizes the analog image signal to obtain a digital image signal representing the radiation image; wherein the detection means recognizes a signal component representing the partition walls included in the analog signal, and obtains the digital image signal from the component of the analog signal obtained between the recognized signal components representing the partition walls. 19. A radiation image acquisition apparatus according to claim 18, wherein a phosphor having light conversion characteristics different from the stimulable phosphor is mixed with either the cell partition walls or the stimulable phosphor contained therebetween before the phosphor layer is formed and the signal acquisition means recognizes the signal component representing the partition walls included in the signal obtained by detection of the fluorescent light emitted from the phosphor material in the phosphor layer due to aforementioned scanning. 20. A radiation image acquisition apparatus according to claim 19, wherein the detected signal component representing the partition walls is used as a trigger signal in digitizing the analog image signal to obtain the digital image signal. 21. A radiation image acquisition apparatus according to claim 19, wherein the digital image signal is corrected by being divided by the signal component representing the cell partition walls, wherein said signal component is a sampling time. 22. A radiation image acquisition apparatus according to claim 18, wherein said signal acquisition means recognizes the signal component representing the partition walls included in the signal obtained by detecting the refle