Photoelectric determination of the difference between work functions of metals

On d.c. biasing tunnel diodes under illumination (2537 ¿), we observe a linear dependence of photocurrents on bias and can thus measure the difference between the work functions of the electrodes. It also appears that the barrier lowering of aluminium after oxidation cancels if the ntype zone between Al and Al2O3 is reduced. An explanation is advanced.