JPS63104471A - Seniconductor device - Google Patents

Abstract

PURPOSE:To obtain the semiconductor device which emits light from a quantum well layer by a method wherein the quantum well layer, in which electrons and hole are resonant-tunnelled simultaneously, is interposed between an emitter layer and a base layer. CONSTITUTION:On an n<+> type GaAs substrate 1, an n-type GaAs collector layer 2, a p<+> type GaAs base layer 3, an undoped GaAs spacer layer 4, a quantum well layer 5, an AlAs barrier layer 5B, a GaAs well layer 5W, an undoped GaAs spacer layer 6, an n-type GaAs emitter layer 7, and an n<+> type GaAs emitter contact layer 8 are provided. Then, the quantum well layer 5 consisting of a quantum well layer, with which electrons and hole can be resonant-tunnelled simultaneously by the same base voltage, a barrier layer 5B and a well layer 5W is interposed on a p-n junction interface (the interface of the base layer 3 and the emitter layer 7). The electrons and hole can be stored on the well layer, and a light can be emitted by performing the recoupling of electrons and hole. As said emitted light can be modulated at high speed, the title semiconductor device is suitable for high speed operation of optical communication.

Description

[Detailed Description of the Invention] [Summary] The present invention provides a semiconductor device by interposing a quantum well layer between an emitter layer and a base layer in which electrons and holes can simultaneously tunnel resonantly. Light can be emitted from the well layer in the quantum well layer.

[Industrial application field]

The present invention relates to an improvement in a semiconductor device that utilizes the so-called resonant tunneling effect, which is generated by a well layer and barrier layers sandwiching the well layer.

[Conventional technology]

Currently, resonant tunneling diodes (resonant-tunneling diodes) are semiconductor devices that utilize the resonant tunneling effect.
tunneling diode (RTD), resonant tunneling hot electron transistor (r
esonant-tunneling hot e
electron transistor: RHET)
, resonant tunneling bipolar transistor (re
sonant-tunneling bipolar
transistors (RBT), etc., have been realized, and all of them have new functions and high speeds that cannot be obtained with ordinary semiconductor devices.

Incidentally, among the above-mentioned semiconductor devices, the RBT has a configuration in which a resonant tunneling barrier is inserted at the pn junction surface, and both electrons and holes are involved in its operation.

FIG. 5 represents the energy band diagram of the RBT.

In the figure, E is n-type A 7! G a As emitter layer, QW is quantum well layer, PB is A#As barrier layer, W is GaAs well layer, B is p+ type GaAs base layer, C is n type GaAs collector layer, RLC and RLV are resonance levels , e indicate electrons, respectively. Note that this energy band is based on the base-emitter voltage ■8. ~1.6
(V).

Figure 6 shows the voltage and voltage at the RBT explained in Figure 5.
It represents a diagram regarding current characteristics.

In the figure, the horizontal axis shows the base-emitter voltage VIE, and the vertical axis shows the collector current Ic and base current In.The solid line is the characteristic line regarding the collector current Ic, and the broken line is the base current. 1. This is the characteristic line for .

As is clear from the figure, both the collector current 1c and the base current 1. A peak also appears.

This indicates that a resonant tunneling current has flowed at that point, and needless to say, the collector current ■. In the case of the base current I, the carriers are electrons, and in the case of the base current I, the carriers are holes.

[Problem that the invention seeks to solve]

It is known that in the RT3T quantum well layer QW as described above, many carriers are accumulated in the well layer W in a resonant tunneling state.

7 and 8 are diagrams for explaining that carriers are accumulated in the well layer W. In the case of electrons, FIG.
FIG. 8 shows the case of holes, and the same symbols as those used in FIGS. 5 and 6 indicate the same parts or have the same meanings.

In both figures, the horizontal axis shows the length, and the vertical axis shows the carrier density, and the energy band is also shown, with the solid line showing the energy band, and the dashed line showing the electron. Each represents the concentration or hole concentration.

As is clear from the figure, within the well layer W, the electron concentration or the genuine bill concentration is high.

Based on the above, the present inventors have proposed a method in which electron resonant tunneling and hole resonant tunneling occur simultaneously to create a state in which both the electron concentration and hole concentration in the well layer W are high. If this could be realized, it would be possible to cause recombination of electrons and holes within the well layer W, thereby emitting light.

The present invention aims to provide a semiconductor device capable of emitting light in a quantum well layer forming a resonant tunneling barrier.

[Means for solving problems]

As mentioned above, simultaneous generation of electron resonant tunneling and hole resonant tunneling means that the same base-emitter voltage VIl! This corresponds to the fact that these phenomena must occur together when .

In order to do so, for example, (1) Aβg Ga 1− in the emitter layer E
Appropriately select the X value of zA s, (2) Appropriately select the width of the well layer W, (3)
(4) Barrier layer P appropriately selects failure of well layer W
(5) Appropriately select the width of the barrier layer PB; (6) Appropriately select the barrier height by changing the material that constitutes B; (5) Appropriately select the width of the barrier layer PB;
There are many methods, such as appropriately selecting the impurity concentration in the emitter E, (7) appropriately selecting the impurity concentration in the base B, etc.;
The objective can be achieved by optimizing multiple of them.

Figures 9(A), (B), and (C) and Figures 10 to 12 show the base-emitter voltage V, l at which resonant tunneling of electrons occurs by changing the X value in the emitter layer E.
! This is a diagram for explaining that the resonant tunneling of holes can be changed, and the same symbols as those used in FIGS. Shall have.

Figure 9 (A), (B), and (C) show the emitter layer E.
Al in! , lGa, -, is an energy band diagram when changing the X value of As, (A)
is when x=o, O, (B) is when x=0.1, (C
) indicate the cases where x=o and 2, respectively.

Examples of main data regarding the configuration of the semiconductor device from which this energy hand diagram was obtained are as follows.

(ll) X value for barrier layer PB: 1.O (therefore, AXAS) Thickness: 20 [people] (2) X value for well layer W: 0.0 (therefore, GaAs) Thickness = 50 [people] , the dashed line designated by the symbol RL in the well layer W is the resonance level.

10 to 12 are diagrams representing the relationship between voltage and current corresponding to FIGS. 9(A) to 12(C), and
0 corresponds to FIG. 9(A), FIG. 11 corresponds to FIG. 9(B), and FIG. 12 corresponds to FIG. 9(C).

In each figure, the horizontal axis represents the applied voltage, and the vertical axis represents the current. The long wave line indicated by the symbol e represents the characteristic line related to the current caused by electrons, and the symbol ■ represents the characteristic line related to the current caused by electrons.

The dashed-dotted line indicated by h is the characteristic line for the current due to light holes, the short wave line indicated by the symbol Hh is the characteristic line for the current due to heavy holes, and the solid line indicated by the symbol T is the characteristic line for the total current. are shown respectively.

As is clear from FIGS. 9(A) and 10, when x(if) in the emitter layer E is 0.0, the base
When the voltage applied between the emitters is about 1.82 (V), resonance tunneling of electrons and holes occur simultaneously.

As is clear from FIGS. 9(B) and 11, when the X value in the emitter layer E is O,], when the applied voltage between the base and emitter is approximately The resonant tunneling of electrons also occurs at approximately 1.87 (V)
The resonance of the correct bill when!・Nelling occurs in each case.

As is clear from FIGS. 9(C) and 12, when the X (direction) in the emitter layer is 0.2, resonant tunneling of electrons (IJ) does not occur, and the voltage applied between the base and emitter Resonant tunneling of holes occurs when the voltage is approximately 1.94.(V).

In this manner, by appropriately selecting the X value in the emitter layer E, it is possible to control the occurrence of electron resonant tunneling and hole resonant tunneling. Incidentally, in the semiconductor device targeted in the above description, the emitter layer E
Resonant tunneling of electrons and holes occurs simultaneously when the X value of It goes without saying that things have changed.

From the description of the above experiment, by appropriately selecting the above conditions, it is possible to control electrons and holes to simultaneously tunnel through the resonant tunneling barrier, thereby causing electrons and holes to enter the well layer W. It will be understood that it is possible to accumulate and recombine them there.

Therefore, in the semiconductor device according to the present invention, the pn junction interface (for example, the p+ type GaAs base layer 3 and the n type GaAs base layer 3)
A quantum well layer (for example, a quantum well layer 5 consisting of an Al!As barrier layer 5B and a GaA's well layer 5W) in which electrons and holes can undergo resonance tunneling simultaneously at the same base voltage is provided at the interface with the emitter layer 7). The structure is such that it is inserted.

(Operation) By adopting the above-mentioned means, electrons and genuine cards can be accumulated in the well layer in the quantum well layer, and therefore,
Therefore, electrons and holes can be recombined to emit light, and the light emission can be modulated at high speed due to the characteristics of this type of semiconductor device, making it suitable for increasing the speed of optical communication. Moreover, depending on the voltage applied, it is possible to operate it as a normal RBT without emitting light.
ed circuit:0EIC:).

〔Example〕

FIG. 1 shows a cutaway side view of essential parts in an embodiment of the present invention.

In the figure, 1 is an n+ type GaAs substrate, 2 is an n type GaAs substrate
s collector layer, 3 is a p+ type GaAs base layer, 4 is an undoped GaAs spacer layer, 5 is a quantum well layer, 5B is an AAAs barrier layer, 5W is a GaAs well layer, 6 is an undoped GaAs spacer layer, 7 is a n-type GaAs emitter layer, 8 is n1-type GaAs emitter contact layer, 9
1 indicates an emitter electrode, 10 a base electrode, and 1 a collector electrode.

Examples of the main data of each part are as follows.

(Impurity concentration for 11 substrate 1: 6 x 1018 (cm-') (2)
Thickness for collector layer 2: 5000 (people) Impurity concentration: I x 1017 (am-3) (3) Thickness for base layer 3: 2000C people] Impurity concentration: 5 x 10I8 (cm-3) (4)
Thickness for spacer N4: 200 (people) (5) Barrier layer 5 X value for B: 1.0 Thickness: 20 [people] (6) Well layer 5W Thickness: 50 [people] (7) Spacer layer 6 Thickness: 50 [people] (8) Thickness of emitter layer 7: 1000 (people) Impurity concentration: 5 X l O"(cm-') (9
) Thickness for emitter contact layer 8: 200
0 C person] Impurity concentration: 6 x 10I8 (cm-') Emitter electrode 9 Material: AuGg/Au/WS I Thickness: 200 (person)/1000 [:person]/30
00 (person) αυ Regarding the base electrode 10 Material: A u / Z n / A u thickness: 100
(person) / 100 (person) / 3000 (person) 02) About the collector electrode 11 Material: AuGg/Au Thickness: 200 (person) / 3000 (person) Figure 2 (A) to (C) are Figure 1 This represents an energy band diagram for explaining the operation of the embodiment shown in FIG. 1, and the same symbols as those used in FIGS. Shall have.

In FIG. 2(A), the voltage V required for the base input voltage V to enter a resonance state. , that is, V<
In the case of V□5, electrons e and holes cannot tunnel through the barrier.

In FIG. 2(B), V=V. In case 1, both electrons e and holes undergo resonance tunneling, and the electron and hole concentrations in the well layer 5W become high, where the electrons and holes are recombined to generate light hν. do.

In FIG. 2(C), the case is v>vrlls, and as in the case of FIG. 2(A), electrons e and holes cannot tunnel through the barrier.

FIG. 3 is a diagram for explaining the voltage versus light output characteristics of the embodiment shown in FIG. 1.

In the figure, the horizontal axis represents the voltage V, and the vertical axis represents the optical output P.

As you can see from the diagram, the voltage ■ for the voltage ■ to reach a resonance state
It is clear that the optical output P appears when ro is reached, and it goes without saying that this corresponds to the operating state explained with reference to FIG. 2(B).

Figure 4 is a diagram for explaining the relationship between voltage and current in the operating state of Figure 2 (B), and the symbols and months used in Figure 6 indicate the same parts. or have the same meaning.

In the figure, the horizontal axis represents the voltage V, and the vertical axis represents the current I, and the solid line 4J collector current 1c is
Further, the characteristic line consisting of a dashed-dotted line represents the base current ■3.

From the figure, when a voltage of about 1.8 (V) is applied to the base, the collector current 1c and the base current I6
Since both show peaks, it can be seen that resonant tunneling of electrons and holes occurred at this time.

〔Effect of the invention〕

In the semiconductor device according to the present invention, a quantum well layer in which electrons and holes can simultaneously tunnel resonantly is interposed between the emitter layer and the base layer.

By adopting this configuration, electrons and holes can be accumulated in the well layer of the quantum well layer, and therefore,
Therefore, electrons and holes can be recombined to emit light, and the light emission can be modulated at high speed due to the characteristics of this type of semiconductor device, making it suitable for increasing the speed of optical communication. Furthermore, depending on the applied voltage, it is possible to operate as a normal RBT without emitting light, so it is effective for configuring OFs and ICs, for example.

[Brief explanation of the drawing]

Fig. 1 is a cutaway side view of essential parts of an embodiment of the present invention, and Fig. 2 (A
) to (C) are energy band diagrams for explaining the operation of the embodiment shown in FIG.
Figure 4 is a diagram to explain the voltage vs. optical output characteristics of the embodiment shown in the figure. Figure 5 is an energy band diagram of the RBT, Figure 6 is a diagram regarding the voltage and current characteristics in the RBT explained in Figure 5,
Figures 7 and 8 are diagrams for explaining that carriers are accumulated in the well layer, and Figures 9 (A) to (C) are diagrams for explaining how carriers are accumulated in the well layer. Energy band diagrams for explaining that resonant tunneling can occur simultaneously, Figures 10 to 12
The figures each represent a diagram for explaining the voltage vs. current characteristics corresponding to FIGS. 9(A) to 9(C). In the figure, 1 is an n+ type GaAs substrate, 2 is an n type GaAs substrate
s collector layer, 3 is p+ type GaAs base layer, 4 is undoped GaAs spacer layer, 5 is quantum well layer, 5B is Aj2As barrier layer, 5w is GaAs well layer, 6 is undoped GaAs spacer layer, 7 is n-type GaAs emitter layer; 8 is n+-type GaAs emitter contact layer;
Reference numeral 9 indicates an emitter electrode, 10 a base electrode, and 11 a collector electrode. Patent Applicant Fujitsu Ltd. Representative Patent Attorney Shoji Aitani Representative Patent Attorney Hiroshi Watanabe - Cutaway side view of essential parts of the embodiment Fig. 1 QW Vres V Fig. 3 QW RBT's energy/pan/tire diagram Fig. 5 Diagram regarding voltage/current characteristics of RBT Fig. 6 〉 U ω noku. okf

Claims (1)

[Claims] A semiconductor device comprising a quantum well layer interposed at a pn junction interface in which electrons and holes can undergo resonance tunneling at the same time at the same base voltage.