semiconductor's surface. This led to several more papers (one of them co-authored with Shockley), which estimated the density of the surface states to be more than enough to account for their failed experiments. The pace of the work picked up significantly when they started to surround point contacts between the semiconductor and the conducting wires with electrolytes. Moore built a circuit that allowed them to vary the frequency of the input signal easily. Finally they began to get some evidence of power amplification when Pearson, acting on a suggestion by Shockley, put a voltage on a droplet of glycol borate placed across a p–n junction. Bell Labs' attorneys soon discovered Shockley's field effect principle had been anticipated and devices based on it patented in 1930 by Julius Lilienfeld, who filed his MESFET-like patent in Canada on October 22, 1925. Although the patent appeared "breakable" (it could not work) the patent attorneys based one of its four patent applications only on the Bardeen-Brattain point contact design. Three others (submitted first) covered the electrolyte-based transistors with Bardeen, Gibney and Brattain as the inventors. Shockley's name was not on any of these patent applications. This angered Shockley, who thought his name should also be on the patents because the work was based on his field effect idea. He even made efforts to have the patent written only in his name, and told Bardeen and Brattain of his intentions. Shockley, angered by not being included on the patent applications, secretly continued his own work to build a different sort of transistor based on junctions instead of point contacts; he expected this kind of design would be more likely to be commercially viable. The point contact transistor, he believed, would prove to be fragile and difficult to manufacture. Shockley was also dissatisfied with certain parts of the explanation for how the point contact transistor worked and conceived of the possibility of minority carrier injection. On February 13, 1948, another team member, John N. Shive, built a point contact transistor with bronze contacts on the front and back of a thin wedge of germanium, proving that holes could diffuse through bulk germanium and not just along the surface as previously thought. Shive's invention sparked Shockley's invention of the junction transistor. A few months later he invented an entirely new, considerably more robust, type of transistor with a layer or 'sandwich' structure. This structure went on to