A diode has the characteristic of allowing very little current flow below a certain turn-on voltage, and substantially more current above the turn-on voltage. It has proven difficult to form a large population of vertically oriented p-i-n diodes having a bottom heavily doped p-type region, a middle intrinsic region, and a top heavily doped n-type region with good uniformity of current among the diodes when a voltage above the turn-on voltage is applied. Diodes may be used in memory arrays, as described, for instance, in U.S. patent application Ser. No. 10/326,470 (“the '470 application”), U.S. patent application Ser. No. 10/955,549 (“the '549 application”), and U.S. Pat. No. 6,952,030 (“the '030 patent”), each of which is co-owned and incorporated herein by reference in its entirety for all purposes.
It would be advantageous to form a large population of such upward-pointing diodes having good uniformity, specifically for use in a memory array.