1. A semiconductor device comprising:
a first-conductive-type base layer provided in a substrate having first and second surfaces;
a second-conductive-type collector layer provided on the first surface;
a collector electrode provided on the second-conductive-type collector layer;
a second-conductive-type base layer provided on the second surface;
a second-conductive-type contact layer selectively provided on the second-conductive-type base layer;
trenches provided on the on a side of second surface;
a gate electrode provided in each of the trenches via a gate insulating film;
a first-conductive-type emitter layer provided on the trenches;
an insulating film provided on the gate electrodes; and
an emitter electrode provided on the second surface, and having a non-contact portion partially provided in the first-conductive-type emitter layer.
2. The semiconductor device of claim 1, wherein a surface impurity concentration of the first-conductive-type emitter layer is equal to or more 1\xd71018 cm\u22123 and less 5\xd71019 cm\u22123.
3. The semiconductor device of claim 1, wherein, in a longitudinal direction of the trenches, a ratio of a width of the first-conductive-type emitter layer to a width of the second-conductive-type contact layer is equal to or more 0.6.
4. The semiconductor device of claim 1, wherein a part of the gate electrode contacts emitter electrode.
5. A semiconductor device comprising:
a first-conductive-type base layer provided in a substrate having first and second surfaces;
a second-conductive-type collector layer provided on the first surface;
a collector electrode provided on the second-conductive-type collector layer;
a second-conductive-type base layer provided on the second surface;
a second-conductive-type contact layer selectively provided on the second-conductive-type base layer;
trenches provided on a side of the second surface;
a gate electrode provided in each of the trenches via a gate insulating film;
a first-conductive-type emitter layer provided on the trenches;
an insulating film provided on the gate electrodes; and
an emitter electrode provided on the second surface, and having a portion in ohmic contact and a portion in Schottky contact with the first-conductive-type emitter layer.
6. The semiconductor device of claim 5, wherein
a surface impurity concentration of the portion of the first-conductive-type emitter layer in ohmic contact with the emitter electrode is equal to or more 1\xd71019 cm\u22123, and
a surface impurity concentration of the portion of the first-conductive-type emitter layer in Schottky contact with the emitter electrode is less 1\xd71019 cm\u22123.
7. The semiconductor device of claim 5, wherein the portion of the first-conductive-type emitter layer is brought into ohmic contact with the emitter electrode by arsenic segregation caused at the portion of the first-conductive-type emitter layer.
8. The semiconductor device of claim 5, wherein, in the longitudinal direction of the trenches, a ratio of a width of the first-conductive-type emitter layer to a width of the second-conductive-type contact layer is equal to or more 0.6.
9. The semiconductor device of claim 5, wherein a portion of the gate electrode contacts the emitter electrode.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. An oral care composition comprising an abrasive system, wherein the abrasive system comprises
(a) a first particulate abrasive comprising at least 20 wt % pumice, based on the weight of the oral care composition, having an average particle size of from 20 to 300 microns; and
(b) a second particulate abrasive comprising calcium carbonate having an average particle size of from 2 to 13 microns.
2. The oral care composition according to claim 1 wherein the first particulate abrasive comprises from 20 to 60 wt % pumice, based on the weight of the oral care composition.
3. The oral care composition according to claim 2 wherein the first particulate abrasive comprises from 30 to 50 wt % pumice, based on the weight of the oral care composition.
4. The oral care composition according to claim 1 wherein at least 60 wt % of the pumice, based on the weight of the pumice, has an average particle size of from 90 to 300 microns.
5. The oral care composition according to claim 4 wherein at least 80 wt % of the pumice, based on the weight of the pumice, has an average particle size of from 90 to 300 microns.
6. The oral care composition according to claim 1 wherein the second particulate abrasive comprises calcium carbonate in an amount of from 5 to 40 wt %, based on the weight of the oral care composition.
7. The oral care composition according to claim 6 wherein the second particulate abrasive comprises calcium carbonate in an amount of from 15 to 30 wt %, based on the weight of the oral care composition.
8. The oral care composition according to claim 1 wherein weight ratio of the first particulate abrasive and the second particulate abrasive is within a range from the group consisting of 0.6-5.0:1, 0.7-4.0:1, and 1.0-3.5:1.
9. The oral care composition according to claim 1 wherein the calcium carbonate has an average particle size of from 4 to 10 microns.
10. The oral care composition according to claim 1 wherein the calcium carbonate comprises of a first calcium carbonate with an average particle size of from 4 to 5 microns and a second calcium carbonate with an average particle size of from 9 to 10 microns.
11. The oral care composition according to claim 1 wherein the weight ratio of the first calcium carbonate with an average particle size of from 4 to 5 microns to the second calcium carbonate with an average particle size of from 9 to 10 microns is selected from group consisting of 1.0-1.2:1 and 1.05-1.15:1.
12. The oral care composition according to claim 1 wherein the calcium carbonate comprises natural calcium carbonate particles.
13. The oral care composition according to claim 1 wherein at least a portion of the particles of calcium carbonate comprise natural calcium carbonate have an average particle size of no greater than a dentin tubule of a mammalian tooth.
14. The oral care composition according to claim 1 which further comprises a basic amino acid in free or salt form in an amount effective for treating dental hypersensitivity.
15. The oral care composition according to claim 14 wherein the basic amino acid in free or salt form comprises arginine bicarbonate.
16. The oral care composition according to claim 14 wherein the basic amino acid in free or salt form is present in an amount of from 5 to 15 wt % based on the weight of the oral care composition.
17. The oral care composition according to claim 16 wherein the basic amino acid in free or salt form is present in an amount of from 7 to 12 wt % based on the weight of the oral care composition.
18. The oral care composition according to claim 1 which further comprises an orally acceptable vehicle.
19. The oral care composition according to claim 18 wherein the orally acceptable vehicle comprises glycerin which is present in an amount of from 5 to 20 wt % based on the weight of the oral care composition.
20. The oral care composition according to claim 19 wherein the glycerin is present in an amount of from 10 to 15 wt % based on the weight of the oral care composition.
21. The oral care composition according to claim 1 further comprising a fluoride compound or a source of fluorine ions.
22. The oral care composition according to claim 1 wherein the amount and particle size of the first and second particulate abrasives are selected to provide the oral care composition with a pellicle cleaning ratio (PCR) of at least 59, a radioactive dentin abrasion (RDA) of no more than 250, and a ratio of the pellicle cleaning ratio (PCR) to the radioactive dentin abrasion (RDA) of at least 0.6.
23. The oral care composition according to claim 22 wherein the pellicle cleaning ratio (PCR) is from 70 to 110, the radioactive dentin abrasion (RDA) is from 100 to 140, and the ratio of the pellicle cleaning ratio (PCR) to the radioactive dentin abrasion (RDA) is from 0.6 to 0.8.
24. The oral care composition according to claim 23 wherein the ratio of the pellicle cleaning ratio (PCR) to the radioactive dentin abrasion (RDA) of from 0.64 to 0.8.
25. The oral care composition according to claim 1 wherein the composition is formulated into a dentifrice in the form of a paste.
26. A method of cleaning teeth comprising applying the oral care composition of claim 1 to a tooth surface, the oral care composition being applied as a paste disposed in a prophy cup.
27. The oral care composition according to claim 1, for use in a cleaning teeth, comprising applying the oral care composition to a tooth surface, the oral care composition being applied as a paste disposed in a prophy cup.