High temperature cadmium boracite semiconductor device

An electronic switch comprising:

• a body of cadmium boracite crystal having first and second surfaces, said body fabricated by chemical vapor transport;
• first electrode means electrically contacting said first surface;
• second electrode means electrically contacting said first or second surface, wherein one of said electrodes is silver or silver-coated and the other electrode is free of silver;
• and
• means for maintaining said body of cadmium boracite at a temperature of at least about 300.degree. C., said body and said electrodes exhibit a high electrical resistance state which is independent of applied alternating current or direct current voltage and a low electrical resistance state dependent upon applied alternating current or direct current voltage.

A temperature sensor comprising:

• a body of single crystal cadmium boracite having first and second surfaces;
• first silver electrode means electrically contacting said first surface;
• second silver electrode means electrically contacting said first or second surface;
• and
• means for applying a voltage across said electrode in excess of the threshold voltage of said crystal wherein said crystal changes from a low conductivity state independent of applied voltage to a high conductivity state dependent upon an applied voltage.

An asymmetric electronic device comprising:

• a body of cadmium boracite crystal having first and second surfaces;
• first electrode means electrically contacting said first surface;
• and
• second electrode means electrically contacting said first or second surface, wherein one of said electrodes is silver or silver-coated and the other electrode is free of silver.