Electronic device

#The invention is in the field of structured electrodes for electronic devices, and is particularly useful for vertical type transistor structures or diodes.

#Various types of electronic devices utilize material selection to provide desired charge transmission and injection properties for proper operation. Typically, charge carriers, such as electrons or holes, may be injected from a conducting/metallic electrode into semiconductor elements of the device to thereby provide adjustable electric transmission properties for applications such as switching, current rectifying, etc.

#Generally, two main types of conductor-semiconductor electrical contact are used, Ohmic contact and Shottky contact. The contact behavior is generally determined by electrical properties of the metal electrode and the semiconductor, and at time by geometry or other characteristics of the metal-semiconductor junction.

#In order to better understand the subject matter that is disclosed herein and to exemplify how it may be carried out in practice, embodiments will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which:

#FIG. 1 exemplifies a transistor structure utilizing two-layered patterned electrode according to the conventional configuration;

#FIGS. 2A to 2H exemplify configurations of electronic devices utilizing an electrode structure according to embodiments of the present invention, FIGS. 2A-2G illustrate transistor structure configurations and FIG. 2H illustrates a diode configuration;

#Reference is made to FIG. 1, illustrating an example of transistor structure 10 configured as described in WO 2010/113,163 (assigned to the assignee of the present invention). As shown, the transistor structure 10 is configured as a vertical type transistor and includes source and drain electrodes 12 and 16 and a channel region 16 located therebetween. Additionally, the transistor includes a gate electrode 18 located under the source electrode 12 and separated therefrom by an isolating (dielectric) layer 20. It should be noted that the source and drain electrodes may be replaced between them.

#As shown, the electrode located close to the gate electrode 18, in this example the source electrode 12, is patterned to allow electric field to penetrate into the channel region 14 to thereby increase its effect on charge carrier's mobility through the channel 14. Additionally, the patterned source electrode 12 is formed of two layers 12A and 12B made of different materials having selected different charge injection properties with respect to the channel region 14. Generally, the bottom portion of the source electrode 12A is made of material having high charge injection properties and the top portion 12B is made of material having lower charge injection properties.

#In this connection it should be noted that charge injection properties can generally be defined by the work function or Fermi energy level of a specific injecting material, relative to the energy level of the accepting material into which the charge is injected. The lower the difference in energy level of the materials, the lower the energy gap for charge carriers to “escape” the material, i.e. transfer from one material to the other, and thus the higher the charge injection properties and vice versa.