Negative Resistance in Semiconductors (InSb)

Abstract

We extend the theory of double injection in insulators, derived by Lampert, so as to adapt it to the case of extrinsic semiconductors. This new treatment is shown to agree reasonably well with our experimentally observed features for n⁺p-InSb diodes at low temperature (77°K). Three outstanding features are revealed by the present analysis : (1) The relation of Vᴍ=(1/β)·VᴛH pointed out by Lampert is available only in the case that the recombination density NR is much larger than the free carrier density P₀ (or N₀), i.e., NR>l0⁵·P₀, where Vᴍ and VᴛH are the minimum and maximum voltages respectively, β is the capture rate for electrons and holes. (2) The greater the capture rate β is, the greater the region of the negative resistance becomes. In semiconductors, however, the magnitude of the region is vigorously depedent on a modified recombination density R=NR/P₀ (or NR/N₀). (3) The value of the mobility ratio b=μₙ/μₚ is concerned with a rise in the semicoductor region, and the relation of J∝V² is satisfactory, if b<lO. In the material with high mobility as a case of InSb, however, the current rises steeply in proportion to the several powers of the voltage, e.g. J∝ V⁴, when b=50. As above mentioned, we can sufficiently explain the behavior of double injection in semiconductors or insulators by this treatment.