Photosensitivity of Germanium Electrodes as a Function of Quantum Energy

Abstract

In this work the relative photosensitivities H = | Δφ/F |i=const of a germanium anode and a germanium cathode were determined as a function of quantum energy (Δφ=electrode potential change caused by light, F = quantum flux, measured in quanta/cm2 sec, and i = current density of electrode). The first increase in the photosensitivity H (Eν) of a n-Ge anode occurs at a quantum energy Eν≈0.93 eV, the second increase at Eν≈1.10 eV, and one relative sensitivity minimum at Eν≈1.27 eV. The sensitivity was approximately constant at larger quantum energies. According to earlier experimental results, the slow phase in a dissolution reaction of Ge at a Ge anode is the breaking of the bond. The form of the sensitivity spectrum can therefore be explained on this basis. The holes, which have an excess energy for activation, break the bond of a Ge atom to the lattice immediately and lead to a fast excess reaction and to a strong photosensitivity. The photosensitivity spectrum of a p-Ge cathode is of the same shape as that of a n-Ge anode. One may therefore make a conclusion, that the photoeffect of a Ge cathode is due to the fast dissolution reaction caused by holes with excess energy. The author proposes that this reaction is the dissolution of germanium as germane.