JPS5929462A - Hetero-junction element - Google Patents

Abstract

PURPOSE:To enable to give electron a high degree of mobility by a method wherein superlattice alone is selectively doped in N type, and the electron generating on the interface of hetero-junction is used as a carrier, thereby enabling to increase the flatness of the titled hetero-junction element. CONSTITUTION:A hetero-junction is formed between an N type GaAs, AlAs superlattice 13 and a GaAs 14 by forming a non-doped GaAs-AlAs superlattice 12 on a semiinsulating GaAs substrate 11, and a GaAs-AlAs superlattice 13 on said GaAs-AlAs superlattice 12, and then a high quality non-doped GaAs 14 is formed on the GaAs-AlAs superlattice 13. According to the hetero-junction formed as above, the hetero-junction interface when the GaAs 14 is grown on the superlattice of GaAs and AlAs having the bandgap same as that of Alx Ga(1-x)As is made flat, thereby enabling to contrive accomplishment of high- speed mobility of two-dimensional electron 15 even when the GaAs 14 is constructed as above by using the N type GaAs-AlAs superlattice 13 instead of an N type AlxGa1-xAs.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heterojunction element in a semiconductor device using a heterojunction, in which the flatness of the junction interface is increased to achieve high electron mobility.

In a heterojunction of two semiconductors with different bandgaps, only the semiconductor with a large bandgap is selectively N
It is known that two-dimensional electrons with high mobility are generated at the heterojunction interface by doping the mold. usually,
N-type AtxGa (+ -x)AII and Ga
Heterojunctions with A s are being utilized to conduct research and development into microwave devices and GaAg ICs. below,
N-type ALxGa(1-x)AIl as a heterojunction
Taking GaAs as an example, Figure 1 shows a cross section of a conventional heterojunction of this type. In the figure, (1) is a semi-insulating GaAs substrate, and (2) is a high quality non-doped
1As-, (3) is N-type AtxGa (1-x)As
.

(4) is the above c a A l (2) and Atx Ga
(1-x) These are two-dimensional electrons generated at the heterojunction interface with As (3).

In such a conventional heterojunction, Nuhtx
Ga < 1-X) GILA under All (3)
If there is ll (2), two-dimensional electrons at the junction interface (4)
has a high mobility metal, but on the contrary, N-type AtxGa (1-x
) A II (3) with G a A 5 (2) does not have high mobility. This is c a A 1
1 On top of (2) AtX GIL < s - x >
When As(3) is grown, the heterojunction interface is flat, but GIL(1-x)A8(3)
When a A s (2) is grown, the heterojunction interface is no longer flat, and as a result, the increase in mobility is prevented.The present invention was made in view of the above points. In a semiconductor device 1?t that uses a heterojunction between a superlattice of two semiconductors with different band gaps and a semiconductor with a narrow band gap among the semiconductors constituting this superlattice, only the superlattice is selectively made into N type. The object of the present invention is to provide a heterojunction element in which the flatness of the heterojunction interface is increased by doping and using electrons generated at the heterojunction interface as carriers, thereby increasing the mobility of electrons.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a sectional view of a heterojunction showing an embodiment according to the present invention. In this example, a semi-insulating G&As substrate (11
) with undoped G mAs , kl Am superlattice (
12), and on this GaA3, AtA superinner lattice 2), an N-type GaAs, AtAs superlattice (2) is formed.
13) and further the GaAs, ALA! I
High quality undoped GaAg (14) on superlattice (13)
) by forming υ, N-type GaAs, AtAl1
A heterojunction is created between the superlattice (13) and G a A 5 (14).

Note that (15) ij is a two-dimensional electron.

Thus, according to the heterojunction of the above embodiment, Atx
G with the same bandgap as Ga(1-x)As
A superlattice of a A s and A I A 11 (13
) When GRA n(14) is grown on top of ), the heterojunction interface becomes flat, so as shown in Figure 2, N-type A
txGa (1-x) N-type Ga A instead of A8
By using the superlattice (13) ffi of s and AtAR, high-speed electron mobility can be achieved even when Ga As (14) is 11/1 of the soil.

In addition, in the above, GaAl1+ AtxGa(1-x)A
Although the case of s heterojunction has been described, it goes without saying that the present invention is limited to this and is not limited to V.

As explained above, according to the present invention, in a heterojunction between a superlattice of two semiconductors with different /ζ band gaps and a semiconductor with a narrow band gap among the semiconductors constituting this superlattice, the superlattice By selectively doping only N-type atoms and using the electrons generated at the heterojunction interface as carriers, the flatness of the heterojunction interface increases and electron mobility can be increased.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a heterojunction showing a conventional example, and FIG. 2 is a sectional view of a heterojunction showing an embodiment of the present invention. (11)...Semi-insulating GaAs substrate, (12
)...Non-doped Ga As + AtA 8
Superlattice, (13) --- NuMGaAg, AtA
s superlattice, -(14)...High quality non-doped GaA
s, (15)・φ・Two-dimensional electron 〇 agent Kuzuno
- Figure 1 Figure 2

Claims (1)

[Claims] In a semiconductor device using a heterojunction between a superlattice of two semiconductors with different bandgaps and a semiconductor with a narrow bandgap among the semiconductors constituting the superlattice, only the superlattice is selectively converted to N-type. A heterojunction element 0 characterized in that it is doped and uses electrons generated at the heterojunction interface as carriers.