KR20010004956A - A GaAs-based P-HEMT having low noise and high gain characteristic - Google Patents

Abstract

PURPOSE: A pseudo high electron mobility transistor of a GaSa series with low noise and high gain characteristic is provided to prevent the generation of DX-center and improve the efficiency of an electron supply layer. CONSTITUTION: A pseudo high electron mobility transistor of a GaSa series with low noise and high gain characteristic comprises the following structure. The pseudo high electron mobility transistor of a GaSa series comprises a super lattice layer(20), a buffer layer(21), a channel layer(22), an electron supply layer(23), and a cap layer(24). The electron supply layer(23) comprises a delta-doped GaAs layer. The electron supply layer further comprises the first AlxGa1-xAs layer(23a) provided on the channel layer(22), a GaSa layer(23b) provided on the first AlxGa1-xAs layer, a silicon-deltas doping layer inserted into the GaSa layer, and the second AlxGa1-xAs layer(23c) provided on the GaSa layer.

Description

GaAs-based P-HEMT having low noise and high gain characteristic

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to semiconductor technology, and more particularly to a GaAs-based pseudo high electron mobility transistor (Pseudo High Electron Mobility Transistor, P-HEMT).

P-HEMT is increasingly demanded in the RF transmitter of the RF transmitter of the wireless communication system such as personal portable communication system (IMT-2000), satellite communication, vehicle automatic navigation system, wireless local area network.

In order to fabricate a P-HEMT with low noise and high gain characteristics, an epi-structure may be considered.

1 is a cross-sectional view illustrating an epitaxial structure of Al _x Ga _1-x As / In _x Ga _1-x As P-HEMT according to the related art, which will be described below.

The epitaxial layer of Al _x Ga _1-x As / In _x Ga _1-x As P-HEMT according to the prior art is AlGaAs / GaAs superlattice layer 10, intrinsic GaAs buffer layer 11, intrinsic- The In _x Ga _1-x As channel layer 12, the intrinsic-Al _x Ga _1-x As electron supply layer 13, and the n ⁺ GaAs cap layer 14 are stacked.

In the conventional P-HEMT having such an epi structure, in order to increase the two-dimensional electron density, when the mole fraction x of aluminum (Al) forming the intrinsic-Al _x Ga _1-x As electron supply layer 13 is increased to 0.2 or more A deep trap (DX center) is generated, which causes a problem that the efficiency of the electron supply layer 13 is lowered.

The present invention provides a gallium acetate having a tee-type gate structure that can prevent the occurrence of a deep trap (DX center) generated when the mole fraction (x) of aluminum constituting the electron supply layer is increased to 0.2 or more to increase the two-dimensional electron density. The purpose of providing a ide-based pseudo classical mobility is also a transistor.

1 is an epi structure diagram of Al _x Ga _1-x As / In _x Ga _1-x As P-HEMT according to the prior art.

Figure 2 is an epi structure diagram of Al _x Ga _1-x As / In _x Ga _1-x As P-HEMT according to an embodiment of the present invention.

3 is a current characteristic curve according to the drain-source voltage of Al _0.25 Ga _0.75 As / In _0.25 Ga _0.75 As P-HEMT (0.25 μm × 70 μm unit T-type gate) according to an embodiment of the present invention.

4 is a diagram illustrating transfer conductance and drain current characteristics according to a gate voltage of Al _0.25 Ga _0.75 As / In _0.25 Ga _0.75 As P-HEMT (0.25 μm × 70 μm unit T-type gate) according to an exemplary embodiment of the present invention. curve.

5 is a cut-off current gain and a maximum stable / available gain characteristic curve of Al _0.25 Ga _0.75 As / In _0.25 Ga _0.75 As P-HEMT (0.25 μm × 70 μm unit T-type gate) according to an embodiment of the present invention.

6 is a graph of a minimum noise figure and an associated gain characteristic curve according to a frequency of Al _0.25 Ga _0.75 As / In _0.25 Ga _0.75 As P-HEMT (0.25 μm × 70 μm unit T-type gate) according to an embodiment of the present invention.

* Explanation of symbols for the main parts of the drawings

20: AlGaAs / InGaAs superlattice layer 21: intrinsic-GaAs buffer layer 21

22: intrinsic-In _0.25 Ga _0.75 As channel layer 23: electron supply layer

23a: Intrinsic-Al _0.25 Ga _0.75 As spacer layer 23b: Intrinsic-GaAs layer

23c: intrinsic-Al _0.25 Ga _0.75 As layer 24: n ⁺ GaAs cap layer

A: Si-delta doped layer B: Two-dimensional electron density

The present invention for achieving the above technical problem, in the gallium arsenide-based pseudo high electron mobility transistor having an epi layer including a superlattice layer, a buffer layer, a channel layer, an electron supply layer and a cap layer, the electron supply layer This silicon is characterized in that it comprises a delta doped GaAs layer.

The present invention also provides a gallium arsenide-based pseudo high electron mobility transistor having an epitaxial layer including a superlattice layer, a buffer layer, a channel layer, an electron supply layer, and a cap layer, wherein the electron supply layer is formed on the channel layer. A first Al _x Ga _1-x As layer for a spacer provided, a GaAs layer provided on the first Al _x Ga _1-x As layer, a silicon-delta doped layer inserted in the GaAs layer, and the GaAs And a second Al _x Ga _1-x As layer provided on the layer.

Further, in the first and second Al _x Ga _1-x As layers, the mole fraction (x) of the aluminum (Al) is greater than 0.2, and preferably the mole fraction (x) of the aluminum (Al) is substantially 0.25. Shall be.

Deep traps (DX centers) occur when donor atoms and aluminum atoms coexist, so the spatial separation of these atoms solves the problem. That is, the present invention provides Al _x Ga _1-x As electrons in order to maximize the two-dimensional electron density (2-DEG) in the In _x Ga _1-x As channel layer while minimizing the deep trap organic phenomenon caused by the Si-Al bond formation. A Si delta-doped GaAs layer was inserted into the supply layer, thereby realizing GaAs-based P-HEMT having low noise and high gain characteristics.

Hereinafter, preferred embodiments of the present invention will be introduced in order to enable those skilled in the art to more easily carry out the present invention.

2 is a cross-sectional view illustrating an epitaxial structure of Al _x Ga _1-x As / In _x Ga _1-x As P-HEMT according to an embodiment of the present invention.

According to the present embodiment _{Al 0.25 Ga 0.75 As / In 0.25} Ga 0.75 As epilayer of P-HEMT is AlGaAs / InGaAs super lattice layer 20, an intrinsic -GaAs buffer layer 21. As shown, the intrinsic -In _0.25 Ga _0.75 As channel layer 22, intrinsic-Al _0.25 Ga _0.75 As spacer layer 23a, intrinsic-GaAs layer 23b, intrinsic-Al _0.25 Ga _0.75 As layer 23c and n ⁺ GaAs cap layer 24 stacked Structure, and the Si-delta doping layer A is inserted in the intrinsic GaAs layer 23b.

In detail, first, the AlGaAs / GaAs superlattice layer 20 is a structure for stabilizing the epi structure, and the intrinsic-GaAs buffer layer 21 has a thickness of about 1000 μs to serve as a buffer. The intrinsic-InGaAs channel layer 22 has a molar fraction of In of 0.25 for high electron mobility and two-dimensional electron density (B), and its thickness is 100 μs in consideration of the critical thickness.

In particular, in the present invention, the electron supply layer 23 may be formed of an intrinsic-Al _0.25 Ga _0.75 As spacer layer 23a of about 70 GPa, an intrinsic GaAs layer 23b of about 40 GPa, and an intrinsic-Al _0.25 Ga _0.75 As layer of about 350 GPa 23c), and the intrinsic-GaAs layer 23b is Si-delta doped (A).

On the other hand, n ⁺ GaAs cap layer was formed to a thickness of 200Å by doping at a concentration of 2x10 ¹⁸ / cm 3 or more to reduce the source resistance.

The Al _0.25 Ga _0.75 As / In _0.25 Ga _0.75 As P-HEMT (0.25 μm × 70 μm unit T-type gate) of the present embodiment having the epi layer configured as described above had a hole measurement result of electron mobility of 7300. It was cm 2 / V · s, and the two-dimensional electron density was 1.8 × 10 ¹² / cm 2, which was the best GaAs-based P-HEMT ever published.

3 is a graph illustrating a current characteristic curve according to a drain-source voltage of Al _0.25 Ga _0.75 As / In _0.25 Ga _0.75 As P-HEMT (0.25 μm × 70 μm unit T-type gate) according to an exemplary embodiment of the present invention. As shown, it can be seen that it shows excellent current characteristics compared to the previously published GaAs-based P-HEMT.

In addition, Figure 4 is a transmission conductance (transconductance) according to the gate voltage of Al _0.25 Ga _0.75 As / In _0.25 Ga _0.75 As P-HEMT (0.25㎛ × 70㎛ unit T-type gate) according to an embodiment of the present invention ), And maximum drain conductance is 440mS / mm and maximum drain current density is 470mA / mm ² , which is superior to that of GaAs-based P-HEMT. .

Meanwhile, FIG. 5 is a block current gain and maximum stability / availability of Al _0.25 Ga _0.75 As / In _0.25 Ga _0.75 As P-HEMT (0.25 μm × 70 μm unit T-type gate) according to an exemplary embodiment of the present invention. The gain characteristic curve is shown, with a current gain cutoff frequency of 65 GHz and a power gain cutoff frequency of 110 GHz.

In addition, Figure 6 is a minimum noise index according to the frequency of Al _0.25 Ga _0.75 As / In _0.25 Ga _0.75 As P-HEMT (0.25㎛ × 70㎛ unit T-type gate) according to an embodiment of the present invention and related The gain characteristic curve is shown, and it can be seen that the frequency exhibits a high gain and a low noise figure with a characteristic of 0.7 dB at 9 GHz.

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and various substitutions, modifications, and changes can be made in the art without departing from the technical spirit of the present invention. It will be apparent to those of ordinary knowledge.

For example, in the above-described embodiment, the case of Al _0.25 Ga _0.75 As / In _0.25 Ga _0.75 As P-HEMT having a _0.25 μm × 70 μm unit T-type gate has been described as an example. The epi structure is characterized in that it can be applied even if it has a different gate structure.

The present invention described above has the effect of maximizing the two-dimensional electron density (2-DEG) in the In _x Ga _1-x As channel layer while minimizing the deep trap organic phenomena due to the Si-Al bond formation, thereby low noise and high gain characteristics. GaAs-based P-HEMT can be implemented.

Claims (4)

In a gallium arsenide-based pseudo high electron mobility transistor having an epi layer including a superlattice layer, a buffer layer, a channel layer, an electron supply layer, and a cap layer, The electron supply layer, A gallium arsenide-based pseudo high electron mobility transistor comprising silicon delta-doped GaAs layer. In a gallium arsenide-based pseudo high electron mobility transistor having an epi layer including a superlattice layer, a buffer layer, a channel layer, an electron supply layer, and a cap layer, The electron supply layer, A first Al _x Ga _1-x As layer for spacers provided on the channel layer; A GaAs layer provided on the first Al _x Ga _1-x As layer; A silicon-delta doped layer embedded in the GaAs layer, A gallium arsenide-based pseudo high electron mobility transistor comprising a second Al _x Ga _1-x As layer provided on the GaAs layer. The method of claim 2, In the first and second Al _x Ga _1-x As layer, A gallium arsenide-based pseudo high mobility mobility transistor, wherein the molar fraction x of aluminum (Al) is greater than 0.2. The method of claim 2, In the first and second Al _x Ga _1-x As layer, A gallium arsenide-based pseudo high mobility mobility transistor, wherein the mole fraction x of aluminum (Al) is substantially 0.25.