it can be seen that dz g dz s u2243 0 01 in the operating range around u t 0 5 v fig8 relates the gap width to the tunneling voltage for the three values 0 1 na 1 na and 10 na of the tunneling current i t it will be apparent from the foregoing description that variations in tunneling current occurring fast as compared to the time constant u03c4 l of the r l c l circuit are not compensated for by the current stabilizer comprising field effect transistor 11 small asperities on the surface 6 of the recording medium 7 topography as well as local changes in workfunction of the recording material therefore will show up in full strength in the tunneling current i t they create a voltage signal u sig across load resistance r l 14 which can be used for further processing of the stored information while the present invention is not directed to the storage medium per se it seems in order to briefly introduce a storage medium capable of recording variations of the tunneling current a suitable storage medium may for example comprise a thin layer of silicon dioxide on top of a silicon substrate the oxide is prepared to have a plurality of trapping sites of about 2 4 ev depth electrons emitted from a tunnel tip can be stably trapped at such sites at room temperature cf d j dimaria in pantelides ed 34 the physics of sio2 and its interfaces 34 pergamon 1978 p 160 et seq this mechanism qualifies for write read.