Russell Ohl Biography -Solar cell inventor

Today we shall look at the biography of Russell Ohl, whose foundational works on semiconductors and p-n junction diodes led to the invention and development of transistors. Russell Ohl was born in January 1898 in Pennyslavia, United States. He was an American Engineer and shoe maker.

The remainder of this biography is culled from ETHW. See link at the bottom.

“Russell Ohl was born in January 1898, near Allentown, Pennsylvania. An extremely bright student, he entered public school at the age of five and went on to what became Pennsylvania State University at age 16. It was in his sophomore year in college that Ohl saw a radio receiver for the first time and heard his first “broadcast”—the SOS from a ship at sea that was being attacked by a German submarine. He was intrigued, but it wasn’t until a year later, when he took a course on electron tubes, that his lifelong passion for radio really began.

After graduation, Ohl served a brief stint in the Army Signal Corps, taught for a while, and then went to work, first at Westinghouse, then AT&T and finally, in 1927, at Bell Labs in Holmdel, New Jersey. It was through Ohl’s work with radio that he became interested in semiconductors.

Russell Ohl
Russell Ohl

In the 1920s radio tuners were only able to receive the relatively low frequencies used for broadcasting. Cutting edge research of radio technology was exploring frequencies above the broadcast band, the frequencies that would later be used for FM, television, microwave communication, and radar. Unfortunately, electron tube transmitters and receivers tended to function poorly at these high frequencies. Ohl wanted to create an improved receiver for high frequencies using semiconductor “detectors,” which were known to outperform electron tubes at these frequencies. Despite reservations among the Bell Labs management, Ohl’s quest eventually led him to experiment with new forms of semiconductor materials such as germanium and silicon.

Samples of semiconductors were refined in small vessels and allowed to cool. Then the crystallized ingot would be removed, cut into slices or slabs, and used for experiments. In 1940 Ohl was working with a silicon sample that had a crack down its middle. He was using an ohmmeter to test the electrical resistance of the sample when he noted that when the sample was exposed to light, the current that flowed between the two sides of the crack made a significant jump. It was known that other semiconductors, such as selenium, generated a small current when exposed to light, but the cracked silicon sample was quite a curiosity. Ohl showed the sample to his colleagues and together they deduced that the crack was a fortunate accident: It marked the dividing line that had occurred when the molten silicon froze in the crucible. At that moment, various impurities or contaminants in the silicon had been isolated into different regions, with the crack separating them.

 

As a result, the silicon atoms in the region on one side of the crack had extra electrons around them. The other region was the opposite; its crystallized silicon had a slight shortage of electrons. They named the two regions p and n—p for positive-type and n for negative-type. The barrier between the impurities was called the p-n junction. The junction represented a barrier, preventing the excess electrons in the n-region from traveling over to the p-region, where atomic forces naturally drew them.”

Culled mainly from ETHW

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Monocrystalline Solar Panel
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