Fabrication of n-type nickel doped B5C1+δ homojunction and heterojunction diodes

Abstract

We have successfully nickel doped a boron carbide ͑B 5 C͒ alloy film. The nickel doped boron-carbide ͑Ni-B 5 C 1ϩ␦) thin films were fabricated from a single source carborane cage molecule and nickelocene ͓Ni͑C 5 H 5) 2 ͔ using plasma enhanced chemical vapor deposition. Nickel doping transforms the highly resistive undoped film from a p-type material to an n-type material. This has been verified from the characteristics of diodes constructed of NiB 5 C 1ϩ␦ on both n-type silicon and p-type B 5 C. The homojunction diodes exhibit excellent rectifying properties over a wide range of temperatures.

The all boron carbide diode neutron detector: Comparison with theory

“…The boron carbide semiconductor fi lms formed after decomposition are clearly self doping materials, since the deposition and decomposition involves only the metacarborane and orthocarborane source molecules (n-type and p-type, respectively), as discussed elsewhere [4]. In fabricating the all boron carbide heteroisomeric or heteropolytype diodes for these studies, no transition metal impurity dopants were introduced as was necessary for the more conventional homojunction boron carbide based diodes [25,26].…”

“…The source molecule gas closo-1,2-dicarbadecaborane (orthocarborane) was used to grow the slightly p-type boron carbide while nickelocene (Ni(C 5 H 5 ) 2 ) was used to introduce nickel into the semiconducting boron carbide fi lm grown in the plasma reactor using orthocarborane (closo-1,2-dicarboadodecaborane (C 2 B 10 H 12 )) fi lm. The inclusion of nickel, from nickelocene (Ni(C 5 H 5 ) 2 ) simultaneously introduced into the plasma reactor with orthocarborane (closo-1,2-dicarboadodecaborane (C 2 B 10 H 12 )) fi lm, resulted in an effective n-type-boron carbide [25,26,28,29]. All boron carbide p-n junction diodes were also fabricated by chemical vapor deposition from two different isomers of closo-dicarbadodecaborane (closo-1,2-dicarbadodecaborane (orthocarborane, C 2 B 10 H 12 ) and closo-1,7-dicarbadodecaborane (metacarborane, C 2 B 10 H 12 )) that differ only by the carbon position within the icosahedral cage.…”

“…There is the conventional homojunction diode where a transition metal dopant is used to dope the semiconducting boron carbide n-type or p-type. The homojunction diode has seen effective realization by doping the semiconducting boron carbide during fi lm growth through plasma-enhanced chemical vapor deposition (PECVD) from a suitable carborane [25,26]. A few all boron carbide devices [4,6], generally from semiconducting boron carbides formed from the decomposition of molecular precursors such as from the decomposition of closo-dicarbadodecaboranes: closo-1,2-dicarbadodecaborane (orthocarborane, C 2 B 10 H 12 ) and closo-1,7-dicarbadodecaborane (metacarborane, C 2 B 10 H 12 ) [4].…”

“…Following the procedure described elsewhere [25,26,28,29], the p-n homojunctions were formed by depositing boron carbide thin fi lms in a custom designed parallel plate 13.56 MHz radio frequency PECVD reactor. The source molecule gas closo-1,2-dicarbadecaborane (orthocarborane) was used to grow the slightly p-type boron carbide while nickelocene (Ni(C 5 H 5 ) 2 ) was used to introduce nickel into the semiconducting boron carbide fi lm grown in the plasma reactor using orthocarborane (closo-1,2-dicarboadodecaborane (C 2 B 10 H 12 )) fi lm.…”

“…All boron carbide p-n junction diodes were also fabricated by chemical vapor deposition from two different isomers of closo-dicarbadodecaborane (closo-1,2-dicarbadodecaborane (orthocarborane, C 2 B 10 H 12 ) and closo-1,7-dicarbadodecaborane (metacarborane, C 2 B 10 H 12 )) that differ only by the carbon position within the icosahedral cage. The diodes were constructed using the process of PECVD (plasma enhanced chemical vapor deposition) as described for both heterojunction [1,[25][26][27][28][29][30] and homojunction diodes [25,26] of boron carbide, but with only carboranes and argon as the plasma reactor gases. The boron carbide semiconductor fi lms formed after decomposition are clearly self doping materials, since the deposition and decomposition involves only the metacarborane and orthocarborane source molecules (n-type and p-type, respectively), as discussed elsewhere [4].…”