U.S. Philips Corporation

Paulus W Blom

Ronald M Wolf

Marcellinus P Krijn

Jacobus Bernardus Giesbers

Ronald Martin Wolf

Johannes F Cillessen

A semiconductor device includes a transparent switching element (1) with two connection electrodes (2, 3) of a transparent material and an interposed transparent channel region (4) of a semiconductor material provided with a transparent gate electrode (5) of a conductive material, separated from the channel region (4) by a transparent insulating layer (6). The semiconductor material is a degenerate semiconductor material with a basic material having a bandgap (10) between conduction band (11) and valence band (12) of electrons greater than 2.5 eV and a mobility of charge carriers greater than 10 cm.sup.2 /Vs provided with dopant atoms which form a fixed impurity energy level (13) adjacent or in the valence band (12) or conduction band (11) of the basic material. The degenerate semiconductor material is transparent because the absorption of visible light is not possible owing to the great bandgap (10), while also no absorption of visible light takes place through the impurity energy levels (13). The device is capable of comparatively fast switching.

Semiconductor device having a transparent switching element

The invention relates to a tunnel diode provided with two metallically conducting electrodes (1, 2) with an insulating dielectric (3) in between, which forms a barrier with a barrier level for electrons and which has a thickness such that electrons can tunnel through the barrier from the one to the other electrode. Such a tunnel diode has the disadvantage that it has no memory. In many applications it is desirable for the tunnel diode to hold a certain switching state, such as open/closed. According to the invention, the tunnel diode is characterized in that the dielectric (3) comprises a layer of a material which is ferroelectric at room temperature with a remanent polarization which influences the barrier level. It is achieved thereby that the tunnel diode has various switching states in dependence on the remanent polarization of the dielectric (3). The switching state is maintained until the polarization of the dielectric (3) changes.

Tunnel diode with several permanent switching states

A switching element is provided with two electrodes (1, 2) with a semiconducting dielectric (3) therebetween, one electrode (2) having a material which forms a Schottky contact with the semiconducting dielectric (3), while a space charge region (3') of the Schottky contact forms a tunnelling barrier for electrons during operation. It is desirable in many applications for the switching element to hold a certain switching state, such as open or closed, during a longer period. The switching element may then be used, for example, as a memory element. The dielectric (3) includes a ferroelectric material with a remanent polarization which influences a dimension of the tunnelling barrier. In this manner the switching element has various switching states depending on the remanent polarization of the dielectric (3). These switching states are held until the polarization of the dielectric (3) changes.

Growing community of inventors

Eindhoven, Netherlands

Paulus W Blom