Bipolar transistor having base region with coupled delta layers

• US 5,965,931 A
• Filed: 09/15/1994
• Issued: 10/12/1999
• Est. Priority Date: 04/19/1993
• Status: Expired due to Term

• Current Assignee: Regents of the University of California (University of California)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Carns, Timothy K., Zheng, Xinyu, Wang, Kang L.
• Primary Examiner(s): Meier, Stephen D.
• Application Number:
  US08/306,795
• Time in Patent Office: 1,853 Days
• Field of Search: 257/585, 257/572, 257/583
• US Class Current: 257/585
• CPC Class Codes: H01L 29/7371 Vertical transistors
• CPC Class Codes: H01L 29/7373 having a two-dimensional base, e.g. modulation-doped base, inversion layer base, delta-doped base

Abstract

A bipolar transistor includes multiple coupled delta layers in the base region between the emitter and collector regions to enhance carrier mobility and conductance. The delta layers can be varied in number, thickness, and dopant concentration to optimize desired device performance and enhanced mobility and conductivity vertically for emitter to collector and laterally parallel to the delta-doped layers. The transistors can be homojunction devices or heterojunction devices formed in either silicon or III-V semiconductor material.

Claims

1. A bipolar transistor comprising

semiconductor body,

a first region in said semiconductor body of a first conductivity type and forming an emitter region,

a second region in said semiconductor body of said first conductivity type spaced from said first region and forming a collector region,

a third region in said semiconductor body between said first region and said second region and forming a base region, said third region including a plurality of delta-doped layers of a second conductivity type, said delta-doped layers being spaced to allow coupling between delta-doped layers for enhanced mobility and conductivity in a lateral direction of said base region parallel to said first and third regions,

said delta-doped layers extending into the emitter region and into said collector region.

2. The bipolar transistor as defined by claim 1 wherein delta-doped layers of opposite carrier type are placed outside the delta-doped layers in said base region, in said emitter region and in said collector region.

3. The bipolar transistor as defined by claim 1 wherein junctions between emitter, base, and collector regions are homojunctions.

4. The bipolar transistor as defined by claim 1 wherein junctions between emitter, base, and collector regions are heterojunctions.

5. The bipolar transistor as defined by claim 1 and including a base contact laterally engaging each of said delta doped layers.