Motley Fool Rule Breakers recommendation Harris & Harris (NASDAQ:TINY) has always been a difficult company to pin down in terms of value. You see, as a publicly traded venture capital firm specializing in nanotechnology, most of the companies it has taken an equity stake in are in the "pre-revenue" stage. To put it more succinctly, its investments are not yet generating much, if anything, in the way of revenue.

Most investors recognize this, but they are betting that many of these start-ups will begin generating revenue -- big revenue. Recently, I have written about Harris & Harris' investment in both Evolved Nanomaterials Sciences and Cambrios. The former is seeking to help big pharmaceutical firms jump-start their drug discovery process by more efficiently separating chiral molecules, while the latter is attempting to apply its disruptive molecular self-assembly technology to everything from flat-panel displays to batteries.

A third investment now appears to be on the verge of paying off for Harris & Harris. Late last week, Nantero, a nanotechnology company using carbon nanotubes for the development of next-generation semiconductor devices, announced that it had become the first in the world to use carbon nanotubes in mass-production semiconductor fabrication plants.

In the past, Nantero officials had boasted of their ability to align 10 billion carbon nanotubes on a single wafer. This extraordinary feat suggested that the company could create a high-density nonvolatile random access memory with enough power that it could offer a "universal memory" -- a memory so fast that a computer would never have to "boot up," and so powerful that it could replace all existing forms of memory, including DRAM, SRAM, and flash.

The big question, though, was whether Nantero could scale this method to a level where large semiconductor manufacturers would feel confident using it in their existing manufacturing processes.

With this announcement, it appears that the company has satisfactorily addressed this concern. Nantero officials didn't announce which semiconductor manufacturer was employing the technology, but in May of this year the company transferred research work that it was doing for LSI Logic (NYSE:LSI) to On Semiconductor (NASDAQ:ONNN).

Until more details are forthcoming, investors are cautioned against getting too excited. But if you are already an investor in Harris & Harris or are considering an investment, this news offers compelling evidence that the company remains one of the best "pure play" nanotech investments on Wall Street today.

The market for memory products is estimated to be more than $100 billion, and with the demand for enhanced memory being driven ever higher by everything from high-performance cell phones and MP3 players to digital cameras, the market is likely only to grow larger. If Nantero can capture even a sliver of this massive opportunity, the payout for Harris & Harris and its investors could be significantly larger than the profits it reaped from its early investment in Nanophase (NASDAQ:NANX).

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Harris & Harris is a Motley Fool Rule Breakers recommendation.

Fool contributor Jack Uldrich is the author of two books on nanotechnology, including Investing in Nanotechnology: Think Small, Win Big. He owns stock in Harris & Harris. The Fool has a strict disclosure policy.