TRANSITION FROM ELECTRODE-LIMITED TO BULK-LIMITED CONDUCTION PROCESSES IN METAL-INSULATOR-METAL SYSTEMS

If a blocking contact exists at a metal-semiconductor interface, the conduction process is electrode-limited and will normally remain so, that is, it will not become bulk-limited with increasing applied voltage unless the semiconductor is inordinately thick. It is shown, however, that in an insulator containing a high density of traps and donors, such as one might expect in evaporated insulating films, the conduction process can change from being electrode-limited to being bulk-limited. This process results at low voltages in a very steep I-V characteristic which is essentially thickness-independent (electrode-limited), and at high voltages in a law Iâexp βV12 which is thickness-dependent (bulk-limited). The results are shown to be in agreement with existing experimental data. © 1968 The American Physical Society.