Browse Prior Art Database

Self-Adjusting Buried-p Layers in Compound Semiconductors

IP.com Disclosure Number: IPCOM000120277D
Original Publication Date: 1991-Mar-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 2 page(s) / 72K

Publishing Venue

IBM

Related People

Hovel, HJ: AUTHOR [+2]

Abstract

Transition metals (Cr, Fe, etc.) have been utilized to create self-adjusting buried-p layers in III-V based devices and, in particular, under the active regions of a GaAs MESFET. Since transition metals are deep acceptors in III-Vs, they are likely to be fully depleted at doses which are typically used in creating a buried-p region in III-Vs. This should minimize parasitic capacitance associated with the region.

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Self-Adjusting Buried-p Layers in Compound Semiconductors

      Transition metals (Cr, Fe, etc.) have been utilized to
create self-adjusting buried-p layers in III-V based devices and, in
particular, under the active regions of a GaAs MESFET.  Since
transition metals are deep acceptors in III-Vs, they are likely to be
fully depleted at doses which are typically used in creating a
buried-p region in III-Vs. This should minimize parasitic capacitance
associated with the region.

      Buried-p layers are formed in MESFET or MOSFET technology to
improve/control short channel effects, threshold voltage uniformity,
K factor and back-gating in the devices.  In GaAs the layers are
typically created by low dose implantation of shallow acceptors, such
as Be or Mg.  The diffusion of implanted Mg or Be in GaAs is
concentration-dependent and is negligible at doses/temperatures

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 used for
creating a buried-p layer in a MESFET.  Since the n-doses in the
channel and source/drain regions are vastly different, p-dopant with
correspondingly different doses would ideally be required to achieve
an optimum control over the carrier profiles in these regions. In
addition, the lateral dopant straggle at the gate edges during the n+
implant creates yet another different dose level between the channel
and source/drain regions.

      In this invention, high diffusivity, damage gettering and
deep-level acceptor cha...