基本信息
摘要：1,269,634. Semi-conductor devices. NATIONAL RESEARCH DEVELOPMENT CORP. 10 June, 1969 [12 June, 1968], No. 28027/68. Heading H1K. A radiation detector comprises a slab of semi-conductor material having a PIN structure and having slots dividing opposite major faces into parallel ribs, the ribs on one face extending transverse to those on the other face, each slot extending to such a depth that it intersects the junction between the respective P- or N- type region and the I-type region. As shown, Fig. 1, a wafer 1 of P-type Ge doped with Ga has a series of parallel slots 5 sawn in one face to form ribs 3 and is etched and ultrasonically cleaned to remove damaged material. A lithium-in-oil suspension is applied to the unslotted face of the wafer which is then heated to diffuse-in the lithium to form an N- type region with an N+ -type surface layer. The PN junction formed is reverse biased to cause the lithium ions to drift-in to form an I- type region 6 between the P- and N-type regions. Slots 4 extending at right angles to the slots 5 are then sawn in the upper face of the wafer to form ribs 2. The wafer is then etched and quenched in an aqueous solution of CaCl 2 , these steps being performed in such a manner that both sides of the wafer are exposed to the fluids. This may be achieved by using a stoppered funnel, Fig. 3 (not shown), or by supporting and rotating the wafer in the etch by means of a nylon clamp engaging the edges of the wafer. The wafer is then given a known clean-up drift. The ribs 2 and 3 are contacted by applying an In-Ga eutectic to the surfaces and pressing on to each face a flexible insulating base, e.g. of fibreglass or plastics material, carrying goldplated contact strips tinned with indium. The In-Ga euteetic alloys to the P-type ribs 3 to provide a low-resistance P-type surface layer. The process steps are controlled so that the sets of grooves 4, 5 intersect the NI and PI junctions respectively, to form an array of PIN diodes with co-ordinate connections. A gamma-ray camera. Fig. 2 (not shown), comprises a PIN diode array mounted with its lower face ribs (3) in thermal contact with a. plate (13) cooled by liquid nitrogen. A bias supply is connected via resistors. (8, 9) to the ribs (2, 3) so that the diodes are reverse biased. A gamma-ray source is viewed through a parallel hole collimator (7) the holes of which are aligned with the diodes of the array. Incidence of a gamma ray on a diode produces pulses at those electrodes. connected to the two ribs the intersection of which defines the diode. These output pulses are amplified and applied to a logic circuit which provides an output indicating the position of the point of the array on which the gamma ray impinged.
摘要附图：
