EFFECT OF A FIELD-INDEPENDENT POLARIZATION DISCONTINUITY ON HETEROJUNCTION CHARACTERISTICS

A new utilization of the basic semiconductor heterojunction is proposed which is based on the mechanism of a field-independent polarization discontinuity P at the interface of a p-n heterojunction. Variations in P yield changes in the space-charge regions and the associated barrier voltages at the interface. By proper choice of the heterojunction parameters, the barrier voltage change can be made approximately linear with P over a finite range. The barrier voltage variation modulates the I-V characteristic of the heterojunction for the case of a positive reverse interface barrier, and modifies the C-V relation in all cases. Typical values are calculated for the properties of the general polarization discontinuity heterojunction, and of a strain-sensitive unit which utilizes a piezoelectric interaction. For the latter, the calculated differential sensitivities are 102 to 103 and 104 to 105 volts per unit strain for the barrier voltage and device output voltage, respectively. This output voltage sensitivity is 1 to 2 orders of magnitude larger than that available in piezoresistive strain gages. This device concept has potential in a variety of technically important areas ranging from mechanical instrumentation to sequentially excited light-emitting arrays. The heterojunction configuration is compatible with both evaporated and epitaxial semiconductor technology, and materials with the necessary combination of physical properties are represented among the well-known II-VI and III-V compounds. Copyright © 1969 by The Institute of Electrical and Electronics Engineers, Inc.