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Nonvolatile Schottky Diode with Barrier Height Controlled by Ferroelectric Polarization

IP.com Disclosure Number: IPCOM000075464D
Original Publication Date: 1971-Sep-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 43K

Publishing Venue

IBM

Related People

Chang, LL: AUTHOR [+2]

Abstract

A semiconductor device consisting of a metal-ferroelectric layer-semiconductor, which has a bistable-nonvolatile memory capability is disclosed. The structure shown in Fig. 1 consists of a thin layer of ferroelectric material 1 sandwiched between a metal 2 and a semiconductor substrate 3. Thin ferroelectric layer 1 can sustain a potential but exhibits a relatively low resistance possibly due to tunneling. Figs. 2A and 2B show the energy diagrams of a structure with an N-type semiconductor. Fig. 2A shows the structure when the ferroelectric layer is under reverse polarization (RP) and 2B shows the structure when the ferroelectric layer is under forward polarization (FP). An important parameter here is the barrier height phi(B) which governs the transport process. Now, as shown in Figs.

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Nonvolatile Schottky Diode with Barrier Height Controlled by Ferroelectric Polarization

A semiconductor device consisting of a metal-ferroelectric layer- semiconductor, which has a bistable-nonvolatile memory capability is disclosed. The structure shown in Fig. 1 consists of a thin layer of ferroelectric material 1 sandwiched between a metal 2 and a semiconductor substrate 3. Thin ferroelectric layer 1 can sustain a potential but exhibits a relatively low resistance possibly due to tunneling. Figs. 2A and 2B show the energy diagrams of a structure with an N-type semiconductor. Fig. 2A shows the structure when the ferroelectric layer is under reverse polarization (RP) and 2B shows the structure when the ferroelectric layer is under forward polarization (FP). An important parameter here is the barrier height phi(B) which governs the transport process. Now, as shown in Figs. 2A and 4B, a charge +/-P induced on the ferroelectric layer surface adjacent to the semiconductor should be compensated by the space charge, Q(sc), and the surface state charge Q(ss) of the semiconductor giving rise to a change in the barrier height phi(B).

The expressions relating Q(sc) and Q(ss) to phi(B) are given by Q(sc) - (2(q) epsilon(s) N(D) phi(B))/1/2/ and Q(ss) - qD(s)(Eg - q phi(B)). where D(s) is the surface state density per unity energy; typically 10/13//cm/2/-eV on silicon.

Without ferrolelectric layer 1, the barrier height is assumed to be determined by the condition Q(sc) = Q(s...