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US 5,308,996 AGranted
TFT device
AssigneeCanon Kabushiki Kaisha
InventorsSatoshi Itabashi, Masaki Fukaya, Toshiyuki Komatsu, Yoshiyuki Osada, Ihachiro Gofuku
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Abstract
A TFT device has an insulation substrate, a semiconductor layer formed on the insulation substrate, a pair of opposed electrodes formed on the semiconductor layer, and a gate electrode formed on the semiconductor layer with an insulation film interposed therebetween, wherein a region doped with at least one type of impurity selected from atoms belonging to the V group of the periodic table is formed in the semiconductor layer at the vicinity of the interface between the semiconductor layer and the insulation layer.
Claims19
A photoelectric converter responsive to a light source comprising:
- (i) a photosensor providing enhanced photocurrent and light response having:
- (a) a semiconductor layer no greater than about 5000.ANG. in thickness containing amorphous silicon, said semiconductor layer forming electrons and holes upon interception of incident light containing optical information;
- (b) a pair of opposed main electrodes in electrical contact with said semiconductor layer;
- (c) a gate electrode;
- (d) an insulation film transparent to said incident light interposed between said semiconductor layer and said gate electrode;
- wherein said semiconductor layer having a region comprising silicon and at least one type of impurity selected from atoms belonging to Group V of the periodic table formed in said semiconductor layer at the vicinity of a first interface between said semiconductor layer and said insulation film;
- said first interface subject to accumulation of said holes upon said interception of said incident light;
- said region having a depth up to 1000 .ANG. as measured from said interface and wherein from 0.1 to 1000 ppm of said impurity being present in said region;
- said region serving as (1) a barrier preventing said holes from moving said first interface in order to increase photocurrent gain and (2) storing said holes at a potential well at a second interface between said region and said semiconductor layer to enhance light response;
- and
- (ii) means for maintaining said gate electrode at an electrical potential lower than said main electrodes at least during a period in which an image signal, which corresponds to said optical information which has been subjected to photoelectric conversion, is read.
8 more elements
A photoelectric converter responsive to a light source comprising:
- (i) a photosensor providing enhanced photocurrent and light response having:
- (a) a first semiconductor layer no greater than about 5000 .ANG. in thickness containing amorphous silicon, said semiconductor layer forming electrons and holes upon interception of incident light containing optical information;
- (b) a pair of opposed main electrodes in electrical contact with said first semiconductor layer;
- (c) a first gate electrode;
- (d) a first insulation film transparent to said incident light interposed between said first semiconductor layer and said first gate electrode;
- wherein said first semiconductor layer having a first region comprising silicon and at least one type of impurity selected from atoms belonging to Group V of the periodic table formed in said first semiconductor layer at the vicinity of a first interface between said first semiconductor layer and said first insulation film;
- said first interface subject to accumulation of said holes upon said interception of said incident light;
- said first region having a depth up to 1000 .ANG. as measured from said interface and wherein from 0.1 to 1000 ppm of said impurity being present in said first region;
- said first region serving as (1) a barrier preventing said holes from moving to said first interface in order to increase photocurrent gain and (2) storing said holes at a potential well at a second interface between said first region and said first semiconductor layer to enhance light response;
- (ii) means for maintaining said first gate electrode at an electrical potential lower than that of said main electrodes at least during a period of which an image signal which corresponds to optical information which has been subjected to photoelectric conversion, is read;
- (iii) a drive element having a second semiconductor layer containing amorphous silicon, a pair of opposed main electrodes in contact with said second semiconductor layer, a second gate electrode, a second insulation film interposed between said second semiconductor layer and said second gate electrode, said second semiconductor layer having a second region comprising silicon and at least one type of impurity selected from atoms belonging to Group V of the periodic table formed in said second semiconductor layer at the vicinity of an interface between said second semiconductor layer and said second insulation film;
- said second semiconductor layer being no greater than about 5000 .ANG. in thickness and containing amorphous silicon, said second semiconductor layer forming electrons and holes upon interception of incident light containing optical information;
- said second insulation film transparent to said incident light;
- wherein said second semiconductor layer having a second region comprising silicon and at least one type of impurity selected from atoms belonging to Group V of the periodic table formed in said second semiconductor layer at the vicinity of a first interface between said second semiconductor layer and said second insulation film;
- said first interface subject to accumulation of said holes upon said interception of said incident light;
- said second region having a depth up to 1000 .ANG. as measured from said interface and from 0.1 to 1000 ppm of said impurity being present in said second region;
- said second region serving as (1) a barrier preventing said holes from moving to said first interface in order to increase photocurrent gain and (2) storing said holes at a potential well at a second interface between said second region and said second semiconductor layer to enhance light response;
- wherein said drive element is electrically connected to said photosensor;
- a second gate drive means for applying a voltage to the second gate electrode of said drive element, wherein the image signal is read by applying positive voltage to said second gate electrode.
16 more elements
A photoelectric converter responsive to a light source providing enhanced photocurrent and light response comprising:
- (i) a semiconductor later no greater than about 5000 .ANG. in thickness containing amorphous silicon, said semiconductor layer forming electrons and holes upon interception of incident light containing optical information;
- (b) a pair of opposed main electrodes in electrical contact with said semiconductor layer;
- (c) a gate electrode;
- (d) an insulation film transparent to said incident light interposed between said semiconductor layer and said gate electrode;
- wherein said semiconductor layer having a region comprising silicon and at least one type of impurity selected from atoms belonging to Group V of the periodic table formed in said semiconductor layer at the vicinity of a first interface between said semiconductor layer and said insulation film;
- said first interface subject to accumulation of said holes upon said interception of said incident light;
- said region having a depth up to 1000 .ANG. as measured from said interface and wherein from 0.1 to 1000 ppm of said impurity being present in said region, said impurity being distributed so that the impurity concentration gradually increases from said first interface in the direction of layer thickness;
- said region serving as (1) a barrier preventing said holes from moving to said first interface in order to increase photocurrent gain and (2) storing said holes at a potential well at a second interface between said region and said semiconductor layer to enhance light response;
- and
- (ii) means for maintaining said gate electrode at an electrical potential lower than said main electrodes at least during a period in which an image signal, which corresponds to said optical information which has been subjected to photoelectric conversion, is read.
7 more elements
A photoelectric converter responsive to a light source providing enhanced photocurrent and light response comprising:
- (i) a semiconductor layer no greater than about 5000 .ANG. in thickness containing amorphous silicon, said semiconductor layer forming electrons and holes upon interception of incident light containing optical information;
- (b) a pair of opposed main electrodes in electrical contact with said semiconductor layer;
- (c) a gate electrode;
- (d) an insulation film transparent to said incident light interposed between said semiconductor layer and said gate electrode;
- wherein said semiconductor layer having a region comprising silicon and at least one type of impurity selected from atoms belonging to Group V of the periodic table formed in said semiconductor layer at the vicinity of a first interface between said semiconductor layer and said insulation film;
- said first interface subject to accumulation of said holes upon said interception of said incident light;
- said region having a depth up to 1000 .ANG. as measured from said interface and wherein from 0.1 to 1000 ppm of said impurity being present in said region;
- said impurity being distributed so that the impurity concentration decreases from said first interface in the direction of layer thickness;
- said region serving as (1) a barrier preventing said holes from moving to said first interface in order to increase photocurrent gain and (2) storing said holes at a potential well at a second interface between said region and said semiconductor layer to enhance light response;
- and means for maintaining said gate electrode at an electrical potential lower than said main electrodes at least during a period in which an image signal, which corresponds to optical information which has been subjected to photoelectric conversion, is read.
7 more elements
A photoelectric converter responsive to a light source having enhanced photocurrent and light response comprising:
- (a) a photosensor unit comprising a first semiconductor layer have a photoelectric conversion region;
- a first pair of main electrodes;
- and a first gate electrode provided on said photoelectric conversion region by means of a first insulating layer;
- (b) a capacitor unit for storing electric signals corresponding to optical information to be subjected to photoelectric conversion at said photosensor unit having a second semiconductor layer;
- a second insulating layer;
- a second pair of electrodes provided on said second semiconductor layer by means of a second insulating layer;
- and
- (c) a transistor unit for reading the electric signals stored in said capacitor unit having a third semiconductor layer, a third pair of main electrodes, and a third gate electrode provided on said third semiconductor layer by means of a third insulating layer;
- wherein said first, second and third semiconductor layers of said photosensor unit, said capacitor unit and said transistor unit are continuously formed, each of said continuously formed first, second and third semiconductor layers have at least one region including Group V atoms at an interface to each said first, second and third insulating layers of each said photosensor unit, capacitor unit, and transistor unit;
- each said semiconductor layer no greater than about 5000 .ANG. in thickness containing amorphous silicon, each said semiconductor layer forming electrons and holes upon interception of incident light containing optical information;
- each said insulating layer transparent to said incident light wherein each said semiconductor layer having said region comprising silicon and at least one type of impurity selected from atoms belonging to Group V of the periodic table formed in each said semiconductor layer at the vicinity of a first interface between each said semiconductor layer and each said insulating layer;
- said first interface subject to accumulation of said holes upon said interception of said incident light;
- each said region having a depth up to 1000 .ANG. as measured from said interface and wherein from 0.1 to 1000 ppm of said impurity being present in each said region;
- each said region serving as (1) a barrier preventing said holes from moving to each said first interface in order to increase photocurrent gain and (2) storing said holes at a potential well at a second interface between each said region and each said semiconductor layer to enhance light response;
- and
- (d) means for maintaining said first gate electrode at an electrical potential lower than each said pair of main electrodes at least during a period in which an image signal, which corresponds to optical information which has been subjected to photoelectric conversion, is read.
13 more elements
Dependencies are inferred from the claim text.