JPS58197770A - Semiconductor device - Google Patents

Abstract

PURPOSE:To increase the amplification factor of a unipolar transistor as well as to reduce the noise thereof by a method wherein an n-AlyGA1-yAs is superposed on an n-AlxGa1-xAs, and an n-Aly'Ga1-y'As and an n-Alx'Ga1-x'As are superposed through the intermediary of an n type Ga layer, and composition ratio of x-y' are properly selected. CONSTITUTION:The barrier 1 of an n-AlyGa1-yAs is contacted with the emitter layer E of an n-AlxGa1-xAs and an n-Ge base layer B is superposed thereon. Subsequently, the barrier 2 of an n-Aly'Ga1-y'As is contacted with the above, an n-Alx'Ga1-x'As collector layer C is superposed, and they are selected into o>=x, x'>=y and y'. The As can be doped in extreme high density and the base width can also be reduced markedly by using Ge for the base B. Also, as a forbidden band width increases when the composition of Al is increased and the effective barrier when viewed from the base B is increased in height, the possibility of dropping of an electron to the conduction band level of the base region is little, and the possibility of running to a collector C as a hot electron increases. According to this constitution, the characteristics of a supersonic transistor can be improved remarkably.

Description

[Detailed description of the invention] The present invention relates to semiconductor devices, particularly transistors.

For example, a GaAs bipolar transistor has A 'l n
Although a pn structure is adopted, A1GaAs tt, which has a wider forbidden band width than GaAs, is provided in the emitter region in order to reduce current loss due to hole injection from the pace region to the emitter region and improve the layer filling ratio. There is something.

In this case, the larger the difference between AffiGaAs and GaAs f) Prefectural coverage, the better, but if it is too large, Affi
The electron mobility in QaAs suddenly drops to 11, causing an increase in emitter resistance and deteriorating device characteristics.
゜On the other hand, as shown in the energy band diagram in Figure 1 (the figure shows only the upper conduction band), n+ type GaAs is used as a pace region (B) in 5, and the emitter region (g) and collector of n type QaAa on both sides of the pace region (B). In region (C), there is a disturbance vi! due to AlQa film 2 which has a larger inhibition i- than GaAs, respectively. A unipolar transistor in which regions 11) and (2) are provided, and the electrons injected from the ivy region <m> flow as hot electrons directly to the collector region (C) over the barrier of the collector region (C) lit. (commonly known as hot electron transistors p; IgDM Technical Dig
est, 629 m (1980) has been proposed. In addition, there is no barrier layer, and the emitter region, base region, and collector region are made of n-type GaAs and n-type G, respectively.
Transistors made of e- and n-type QaAs were also
No. 0-4181 proposes ``'C. However,
In the unipolar transistor, the base voltage If!
Since (B) is a GJIAI, there is a limit to the pace width, and this limit of the base ring causes a decrease in the amplification rate and an increase in noise, and further improvement of the characteristics is desired.

In view of the above points, the present invention provides a semiconductor device and a unipolar transistor with further improved characteristics.

In the present invention, as shown in the energy band wA (only the upper conduction band is shown) in FIG. Emitter-side barrier region (1) of the first conductivity type of ``1-yA@, base region (B) of the first conductivity type of Ge, collector-side barrier region (2) of the first conductivity type of Ga1-yAi ) and AI X'G511-
'AI's first conductive collector region (C) (selected as 0≦X*X'<Yr Y')
. Each emitter region (N), base region (B) and collector region (C) is provided with an electrode, respectively.
) is applied to send the majority carriers to the collector region (C). Here, the regions on the side of each electrode in the emitter region (K) and collector region (C) are AIzGll- of the first conductivity type with the concentration of
It is possible to configure zAm and Alz (jal-1Aa).

Examples of each of the above areas are shown below. The emitter region (M) is formed of n-type QaAs (iA control wheel 14 eV), with a thickness of 1 to 3 μm and an impurity concentration of ~10 cm.
degree. The emitter side barrier region ill is n-type AgGa
As (AI increases ii * system obi is thick
The III-limiting width of As is 2.2@V), the thickness is 100 to 1000X, and the impurity concentration is about 10 Cm-''. Here, the thickness is 100
0! If it is thicker, the resistance increases, and if it is thinner than loo l, the effective height of the barrier is low (the base region (B) is n
+ type Ge (forbidden zone 66 V), its thickness is 100X or less, and the impurity concentration is ~IQ cm-''.
Similarly to 1), it is formed of n-type AlAs, and its thickness is selected to be 2 to 5 fim including the collector region (C).
The impurity concentration is set to 1016 cm-3 or less, at which carriers (electrons in this case) move at a saturation speed. The collector region (C) is formed of n-type GaAs (thickness and impurity concentration are the same as above).

Note that the barrier regions (1) and (2) are AtGmAg.
Besides, Zn8e, InQslAIP, etc. can also be used.

According to the unipolar transistor having such a configuration, it is possible to improve the characteristics of the type of transistor, especially by using KGe in the base region (B). IKJ, the insect is As impurity 10 C1n-J! Compared to GtAs, impurities can be doped at a higher concentration than GtAs, so it is possible to dope with 10"Cm-"
The 4° QiAs Hex region and the Ge Hess region can reduce the base resistance to about /100 with the same base resistance. On the other hand, due to the barrier of the same material, the specific Held and Φ base has a larger [effective barrier seen from the pace] than the G1As pace, so electrons from the Eitzta region (E) move into the conduction band of the base region. The probability of falling to the level is low (
, there is a high probability that the hot electrons will flow as hot electrons over the barrier on the collector side into the collector region (C).

As described above, according to the present invention, in a unipolar transistor having a barrier region with a larger forbidden band width on one side of the base region, the amplification factor is further improved and the noise is reduced. When applied to transistors, it brings about dramatic improvements in characteristics.

[Brief explanation of the drawing]

Figure 111 is an energy band diagram showing an example of a conventional unipolar transistor (t, electron transistor), and Figure JII2 is an energy band diagram showing an example of a unipolar transistor according to the present invention. (k!J) is the emitter region, (B) is the base region, (c
) is the collector region, and IIJ i21 is the barrier region.

Claims (1)

[Claims] AIXGII-XAI f)
$111 area of iris 1 conductivity type, MujiyQ11-yAs
I) A second region of the first conductivity type, a third region of the first conductivity type of A, and a jl of the first conductivity type of At y'Ga 1- y'As.
I4 area and A Fuji X'G! The fifth region of the first conductivity type (where 0≦x, x'<y, y') and the first, fl13, and irises 5 regions are provided with electrodes, respectively, and the first region A semiconductor device comprising means for sending majority carriers of to the S* region.