Method for making a semiconductor device including a superlattice having at least one group of substantially undoped layers
A method for making a semiconductor device may include forming a superlattice including a plurality of stacked groups of layers. Each group of the superlattice may include a plurality of stacked base semiconductor monolayers defining a base semiconductor portion and an energy band-modifying layer thereon. Moreover, the energy-band modifying layer may include at least one non-semiconductor monolayer constrained within a crystal lattice of adjacent base semiconductor portions. At least one group of layers of the superlattice may be substantially undoped.
1 . A method for making a semiconductor device comprising:
forming a superlattice comprising a plurality of stacked groups of layers;
each group of layers of the superlattice comprising a plurality of stacked base semiconductor monolayers defining a base semiconductor portion and an energy band-modifying layer thereon;
the energy-band modifying layer comprising at least one non-semiconductor monolayer constrained within a crystal lattice of adjacent base semiconductor portions;
at least one group of layers of the superlattice being substantially undoped.
2 . The method of claim 1 wherein the at least one group of layers of the superlattice has a dopant concentration of less than about 1×10 15 cm −3 .
3 . The method of claim 2 wherein the at least one group of layers of the superlattice has a dopant concentration of less than about 5×10 14 cm −3 .
4 . The method of claim 1 further comprising forming regions for causing transport of charge carriers through the superlattice in a parallel direction relative to the stacked groups of layers.
5 . The method of claim 1 wherein the superlattice has a common energy band structure therein.
6 . The method of claim 1 wherein each base semiconductor portion comprises silicon.
7 . The method of claim 1 wherein each energy band-modifying layer comprises oxygen.
8 . The method of claim 1 wherein each energy band-modifying layer is a single monolayer thick.
9 . The method of claim 1 wherein each base semiconductor portion is less than eight monolayers thick.
10 . The method of claim 1 wherein the superlattice further has a substantially direct energy bandgap.
11 . The method of claim 1 wherein the superlattice further comprises a base semiconductor cap layer on an uppermost group of layers.
12 . The method of claim 1 wherein all of the base semiconductor portions are a same number of monolayers thick.
13 . The method of claim 1 wherein at least some of the base semiconductor portions are a different number of monolayers thick.
14 . The method of claim 1 wherein all of the base semiconductor portions are a different number of monolayers thick.
15 . The method of claim 1 wherein each base semiconductor portion comprises a base semiconductor selected from the group consisting of Group IV semiconductors, Group III-V semiconductors, and Group II-VI semiconductors.
16 . The method of claim 1 wherein each energy band-modifying layer comprises a non-semiconductor selected from the group consisting of oxygen, nitrogen, fluorine, and carbon-oxygen.
17 . The method of claim 1 wherein forming the superlattice comprises forming the superlattice adjacent a substrate.
18 . A method for making a semiconductor device comprising:
forming a superlattice comprising a plurality of stacked groups of layers; and
forming regions for causing transport of charge carriers through the superlattice in a parallel direction relative to the stacked groups of layers;
each group of layers of the superlattice comprising a plurality of stacked base semiconductor monolayers defining a base semiconductor portion and an energy band-modifying layer thereon;
the energy-band modifying layer comprising at least one non-semiconductor monolayer constrained within a crystal lattice of adjacent base semiconductor portions;
at least one group of layers of the superlattice having a dopant concentration of less than about 1×10 15 cm −3 .
19 . The method of claim 18 wherein the at least one group of layers of the superlattice has a dopant concentration of less than about 5×10 14 cm −3.
20 . The method of claim 18 wherein each base semiconductor portion comprises silicon.
21 . The method of claim 18 wherein each energy band-modifying layer comprises oxygen.
22 . The method of claim 18 wherein each energy band-modifying layer is a single monolayer thick.
23 . A method for making a semiconductor device comprising:
forming a superlattice comprising a plurality of stacked groups of layers;
each group of layers of the superlattice comprising a plurality of stacked base silicon monolayers defining a base silicon portion and an energy band-modifying layer thereon;
the energy-band modifying layer comprising at least one oxygen monolayer constrained within a crystal lattice of adjacent base silicon portions;
at least one group of layers of the superlattice being substantially undoped.
24 . The method of claim 23 wherein the at least one group of layers of the superlattice has a dopant concentration of less than about 1×10 15 cm −3 .
25 . The method of claim 24 wherein the at least one group of layers of the superlattice has a dopant concentration of less than about 5×10 14 cm −3 .
26 . The method of claim 23 further comprising regions for causing transport of charge carriers through the superlattice in a parallel direction relative to the stacked groups of layers.
27 . The method of claim 23 wherein each energy band-modifying layer is a single monolayer thick.