US 12,237,137 B2
Method and apparatus for reducing the work function of polycrystalline metal hexaboride
Pedro P. Guerrero Vela, Pasadena, CA (US); and James E. Polk, Pasadena, CA (US)
Assigned to California Institute of Technology, Pasadena, CA (US)
Filed by California Institute of Technology, Pasadena, CA (US)
Filed on Apr. 2, 2021, as Appl. No. 17/221,170.
Prior Publication US 2022/0328274 A1, Oct. 13, 2022
Int. Cl. H01J 1/02 (2006.01); C04B 41/00 (2006.01); C04B 41/91 (2006.01); H01J 1/146 (2006.01); H01J 9/04 (2006.01)
CPC H01J 1/146 (2013.01) [C04B 41/0054 (2013.01); C04B 41/009 (2013.01); C04B 41/91 (2013.01); H01J 1/025 (2013.01); H01J 9/042 (2013.01); C04B 2235/3804 (2013.01)] 23 Claims
OG exemplary drawing
 
1. A method for treating a polycrystalline material, the method comprising:
exposing a surface of the polycrystalline material to a plasma thereby changing the surface of the polycrystalline material from being characterized by a starting condition to being characterized by a treated condition; wherein:
the surface comprises a plurality of crystallites each having a composition MB6, M being a metal element;
the plasma comprises ions, the ions being characterized by an average ion flux selected from a range of 1.5 to 100 A/cm2 and an average ion energy that is less than a sputtering threshold energy of the plurality of MB6 crystallites in a presence of said plasma;
the starting condition of the surface is characterized by a first average work function and the treated condition of the surface is characterized by a second average work function; and
the second average work function is less than the first average work function.