High Temperature Strain Sensors Based on Gallium Phosphide Whiskers

The study of tensoresistive characteristics of p-type conductivity GaP whiskers with [111] crystallographic orientation that is coincide with the direction of the maximal piezoresistive effect for this material, was carried out. The technology of creating the ohmic contacts to GaP whiskers that allows to use these crystals at high temperatures (400 - 600
⁰
C) was developed. Tensoresistive characteristics of p-type conductivity GaP whiskers were studied in the strain rang ± 1.2 × 10
^-3
rel. un. These studies show that the gauge factor for the whiskers with resistivity 0.025 - 0.03 Ohm×cm 90÷95 at 20
⁰
C. The study of tensoresistive properties show that in the temperature range +20 ÷ +300
⁰
C for p-type conductivity GaP whiskers with resistivity ρ=0.01 - 0.03 Ohm×cm the gauge factor decreased as the temperature rise, but the temperature range 300÷ 550
⁰
C for this crystals very slight temperature dependence of the gauge factor was observed. In this temperature range the temperature coefficient of gage factor is no more than -0.03 %×grad
^-1
. In the temperature range 300 ÷ 500
⁰
C the value of gage factor for this whiskers is high and it equals 40÷50. It could be noticed that in the all investigate temperature range the strain sensors on the basis of p-type conductivity GaP whiskers have the linear dependence resistance vs strain in the strain range ± 5.0× 10
^-4
rel. un. Developed strain sensors on the basis of p-type conductivity GaP whiskers have high mechanical strength at the static and dynamic strain (mire then 10
⁸
cycles), that show their possibility to operate in dynamic mode.