Thin film semi-conductor-on-glass solar cell devices
The present invention relates to semiconductor devices suitable for electronic, optoelectronic and energy conversion applications. In a particular form, the present invention relates to the fabrication of a thin film solar cells and thin film transistors through the advantageous combination of semiconductors, insulators, rare-earth based compounds and amorphous and/or ceramic and/or glass substrates. Crystalline or polycrystalline thin film semiconductor-on-glass formation using alkali ion impurity barrier layer(s) are disclosed. Example embodiment of crystalline or polycrystalline thin film semiconductor-on-glass formation using rare-earth based material as impurity barrier layer(s) is disclosed. In particular, thin film silicon-on-glass substrate is disclosed as the alternate embodiment, with impurity barrier designed to inhibit transport of deleterious alkali species from the glass into the semiconductor thin film.
1. A device for converting radiation to electrical energy comprising;
active layer for converting incident radiation to electrical energy comprising a Group IV semiconductor;
transparent substrate; and
transparent barrier layer consisting of one or more rare earth compounds; wherein the barrier layer separates the active layer and the substrate and substantially prevents unwanted ions from the substrate migrating to the active layer wherein the active layer comprises one or more layers of a large band gap material; and one or more layers of a small band gap material; wherein the large band gap material is chosen from a group consisting of rare-earth oxide (RE x O z ), rare-earth germanium oxide (RE x Ge y O z ), rare-earth silicon oxide (RE x Si y O z ), rare-earth-silicon-oxide-phosphide (RE x Si y O z P w ), rare-earth-silicon-oxide-nitride (RE x Si y O z N w ), rare-earth-silicon-oxide-nitride-phosphide (RE x Si y O z N w P q ) wherein X, Z>0 and Y, W, Q are ≧0, such that the band gap is greater than about 3 eV and wherein said small band gap material is chosen from a group consisting of rare-earth-silicon (RE x Si y ), rare-earth-germanium (RE x Ge y ), rare-earth-phosphide (RE x P y ), and rare-earth-nitride (RE x N y ) and mixtures thereof and wherein X, Y>0 and said small band gap is less than about 3 eV.
2. A device for converting radiation as in claim 1 wherein said active layer comprises at least one lateral p-n junction.
3. A device for converting radiation as in claim 1 wherein said barrier layer comprises at least two layers wherein at least one of the at least two layers has a band gap greater than about 3 eV.
4. A device as in claim 1 wherein the transparent barrier layer comprises a first and second layer wherein the first layer is in contact with the transparent substrate and the second layer is in contact with the active layer and wherein at least one of the first layer and second layer consists of one or more compounds chosen from a group consisting of calcium oxide (CaO), sodium oxide (Na 2 O), potassium oxide (K 2 O), aluminum oxide (Al 2 O 3 ), boron oxide (B 2 O 3 ), zirconium oxide (ZrO 2 ), zircon (ZrSiO 4 ), lead oxide (PbO), alkaline earth metal oxides (AEOx), phosphate glass, phosphorous silicate glass, rare-earth sesquioxide (RE 2 O 3 ), rare-earth dioxide (REO 2 ), rare-earth monoxide (REO), rare-earth nitride (REN), rare-earth oxynitride (REO x N y ), rare-earth phosphide (REP), rare-earth oxyphosphide (REO x P y ), rare-earth carbide (REC y ), rare-earth oxycarbide (REO x C y ), aluminum rare-earth oxide (RE x Al y O w ), rare-earth aluminosilicate (RE x Al y Si z O w ), silicon nitride (SiN x ), (Si x Al y N z ), N:Al 2 O 3 , aluminum oxynitride (AlO x N y ), aluminum nitride (AlN x ), silicon-aluminum-oxynitride (Si z Al v O x N y ), silicon-carbon-nitride (Si z C x N y ), aluminum-carbon-oxynitride (Al z C v O x N y ), silicon, SiO x , rare-earth material, germanium and mixtures of silicon-germanium and combinations and non-stoichiometric combinations thereof.
5. A device as in claim 1 wherein the transparent barrier layer comprises a first and second layer wherein the first layer is in contact with the transparent substrate and the second layer is in contact with the active layer and wherein the first layer consists of one or more a compounds described by [RE] x [RE] y [RE] z [C] m [O] n [N] p [P] r [Si] s [Ge] t [Al] u wherein x>0 and at least one of y, z, m, n, p, r, s, t, or u are >O and RE is a rare earth.
6. A device for converting radiation as in claim 1 wherein the transparent substrate is chosen from a group consisting of sapphire, aluminum oxide (Al 2 O 3 ), diamond (C 4 ), calcium fluoride (CaF 2 ), zircon (Zr x Si 1-x O 4 ), zinc oxide (ZnO), aluminum nitride (AlN), glass, sodium-silicate glass (Na 2 O) x − (SiO 2 ) 1-x , alkali-metal oxides (AMO x ), alkaline-earth metal oxides, a ceramic and crystallized bauxite.
7. A device for converting radiation as in claim 1 wherein the transparent barrier layer comprises a transparent conducting oxide layer.
8. A device for converting radiation as in claim 1 wherein the transparent substrate is flexible.
9. A device for converting radiation to electrical energy comprising;
an active layer for the converting radiation to electrical energy comprising a first semiconductor layer of first conductivity type of thickness between about 30 nm and 150 nm and
a second semiconductor layer of second conductivity type of thickness between about 30 nm and 150 nm;
a transparent barrier layer consisting of one or more a rare earth compounds; and
a substrate transparent to a majority of the radiation for converting, wherein the barrier layer separates the active layer and the substrate such that migration of deleterious species across the barrier layer is functionally impeded and wherein the first and second semiconductor layers comprise one or more layers of a large band gap material; and one or more layers of a small band gap material; wherein the large band gap material is chosen from a group consisting of rare earth (RE x O z ), rare-earth germanium oxide (RE x Ge y O z ), rare-earth silicon oxide (RE x Si y O z ), rare-earth-silicon-oxide-phosphide (RE x Si y O z P w ), rare-earth-silicon-oxide-nitride (RE x Si y O z N w ), rare-earth-silicon-oxide-nitride-phosphide (RE x Si y O z N w P q ) wherein X, Z>0 and Y, W, Q are ≧0, such that the band gap is greater than about 3 eV and wherein said small band gap material is chosen from a group consisting of rare-earth-silicon (RE x Si y ), rare-earth-germanium (RE x Ge y ), rare-earth-phosphide (RE x P y ), and rare-earth-nitride (RE x Ge y ) and mixtures thereof and wherein X, Y>0 and said small band gap is less than about 3 eV.
10. A device as in claim 9 wherein said substrate is chosen from a group consisting of sapphire, aluminum oxide (Al 2 O 3 ), diamond (C 4 ), calcium fluoride (CaF 2 ), zircon (Zr x Si 1-x O 4 ), zinc oxide (ZnO), aluminum nitride (AlN), glass, sodium-silicate glass (Na 2 O) x − (SiO 2 ) 1-x , alkali-metal oxides (AMO x ), alkaline-earth metal oxides, a ceramic and crystallized bauxite.
11. A device as in claim 9 wherein said barrier layer comprises one or more layers wherein at least one of the one or more layers is chosen from a group consisting of calcium oxide (CaO), sodium oxide (Na 2 O), potassium oxide (K 2 O), aluminum oxide (Al 2 O 3 ), boron oxide (B 2 O 3 ), zirconium oxide (ZrO 2 ), zircon (ZrSiO 4 ), lead oxide (PbO), alkaline earth metal oxides (AEOx), phosphate glass, phosphorous silicate glass, rare-earth sesquioxide (RE 2 O 3 ), rare-earth dioxide (REO 2 ), rare-earth monoxide (REO), rare-earth nitride (REN), rare-earth oxynitride (REO x N y ), rare-earth phosphide (REP), rare-earth oxyphosphide (REO x P y ), rare-earth carbide (REC y ), rare-earth oxycarbide (REO x C y ), aluminum rare-earth oxide (RE x Al y O w ), rare-earth aluminosilicate (RE x Al y Si z O w ), silicon nitride (SiN x ), (Si x Al y N z ), N:Al 2 O 3 , aluminum oxynitride (AlO x N y ), aluminum nitride (AlN x ), silicon-aluminum-oxynitride (Si z Al v O x N y ), silicon-carbon-nitride (Si z C x N y ), aluminum-carbon-oxynitride (Al z C v O x N y ), silicon, SiO x , rare-earth material, germanium and mixtures of silicon-germanium and combinations and non-stoichiometric combinations thereof.