JPS6281802A - Oscillator - Google Patents

Abstract

PURPOSE:To attain a stable high frequency oscillation output by providing a resonance circuit between the emitter and base of a hot electron transistor (RHET) utilizing a resonance tunneling effect where a super lattice layer is formed between an emitter layer and a base layer. CONSTITUTION:A resonance circuit (tank circuit) RC is connected between the emitter and collector of an oscillation active element Q being the RHET and a bias is applied by using a bias power supply V1 to cause the resonance tunneling in the super lattice layer formed between the emitter layer and the base layer. The operating region of the oscillation active element Q in this state exists in the negative resistance region and the oscillation output is extracted from the collector side while oscillation is caused between the emitter and base. The resonance tunneling effect is maintained sufficiently even in the terra Herz zone and since the RHET is a 3-terminal element, the oscillation circuit and the output circuit are separated completely an a stable high frequency output is obtained.

Description

[Detailed Description of the Invention] [Summary] The present invention provides a semiconductor device in which carriers resonantly tunnel through a superlattice layer formed between an emitter layer and a base layer in an oscillator, and its emitter base layer. By adopting a configuration that includes a resonant circuit inserted between them and an output end from which an oscillator current is derived from the collector layer of the semiconductor device, high frequency oscillations reaching the terahertz band, for example, can be achieved. Ensure stable continuation.

[Industrial application field]

The present invention describes a hot electron transistor (resonant-tunnel) that utilizes the resonant tunneling effect.
neling hot electron tr
The present invention relates to an oscillator using an oscillating active element (RHET) as an oscillating active element.

[Conventional technology]

Many types of oscillators have been put into practical use to date, but in recent years, as electronic equipment has become faster, there has been a demand for oscillators that can stably continue oscillation at extremely high frequencies.

FIG. 2 is an explanatory diagram of the main part circuit of an oscillator developed with the aim of oscillating at a high frequency.

In the figure, the RTD is a two-terminal resonant tunneling device (
In short, Applied Physics l,
etters, vol, 46 (5) pp508-5
10. Mar, 1. 1985. ), PG is a pulse generator, R is a resistor, L is an inductor, and 0 is an output terminal.

As is clear from the figure, in this oscillator, the oscillation circuit and the output circuit are not separated from each other due to the structure of the resonant tunneling device RTD, which is an oscillation active device.

[Problem that the invention seeks to solve]

Generally, it is estimated that there is no oscillator that can stably continue oscillation at a high frequency, for example, terahertz.

For example, in the oscillator shown in FIG. 2, since the oscillation circuit and the output circuit are shared, it is considered that oscillation becomes unstable.

Ultimately, the biggest reason for this is that there is no device that operates properly as an oscillation active element constituting an oscillator.

The present invention aims to realize an oscillator with a simple configuration and stable operation by using RHET.

[Means for solving problems]

The present inventor has previously provided a RHET with sufficient practicality (see Japanese Patent Application No. 160314/1983 if necessary).

FIG. 3 is a diagram for explaining the RHET, in which (A) is a cut-away side view of the main part, and (B) is an energy band diagram corresponding to diagram (A).

In FIG. 3(A), 1 is an n+ type GaAs collector layer, 2 is A/! , Ga, -, AsD potential barrier layer on the rectifier side, 3 is an n + type GaAs base layer, 4 is a superlattice layer, 5 is an n + type GaAs emitter layer, 6 is an emitter electrode, 7 is a base electrode, and 8 is a collector electrode. Each shows
In FIG. 3(B), E represents the bottom of the conduction band, El represents the Fermi level, and EX represents the energy level of the sub-band.

The superlattice layer 4 is composed of an AlXGa1-XAS barrier layer 4A and a GaAs well layer 4B, and in the example shown, it is composed of two barrier layers and one well layer, but if necessary, multiple well layers can be formed. and a barrier layer may be used to form it.

Figures 4 (A) to (C) represent energy hand diagrams for explaining the operating principle of RHET, and symbols used in Figure 3 indicate the same parts or have the same meaning. shall have it.

In the figure, Ex is a sub-layer generated in the well layer 4B.
The band energy level, q is the charge amount of carriers (electrons), and φ is the conduction band bottom discontinuity value between the collector side potential barrier layer 2 and the base layer 3.
ction band discontinuit
y) and VB indicate the hemi-emitter voltage, respectively.

Figure 4 (A) shows the base-emitter voltage ■1 is 2 Ex
This is an energy band diagram when / is smaller than q (0 or close to O).

In the illustrated state, voltage VCE is applied between the collector and emitter, but since the base-emitter voltage VIIE is almost O, the energy level in the emitter layer 5 is lower than that in the well layer 4B. band energy
Since the level is different from E8, it is impossible for electrons in the emitter layer 5 to tunnel through the superlattice layer 4 and escape to the base layer 3, and therefore no current flows through the RHET.

Figure 4 (B) shows that the base-emitter voltage VIIE is 2.
This is an energy band diagram in the case where EX/q is almost equal.

In the illustrated state, since the energy level in the emitter layer 5 matches the energy level Ex of the sub-band in the well layer 4B, electrons in the emitter layer 5 enter the superlattice due to resonance tunneling effect. Pass through layer 4 to base layer 3
, where the potential energy (0,3(
Since the electrons (eV)) are converted into kinetic energy, the electrons are in a so-called hot state and ballistically pass through the base layer 3 to reach the collector layer l.

Figure 4 (C) shows that the base-emitter voltage VIE is 2 E
Energy band when x/q is larger than
This is a diagram.

In the illustrated state, the energy level in the emitter layer 5 is higher than the sub-band energy level EX in the well layer 4B, so no resonant tunneling effect occurs, and the energy level from the emitter layer 5 to the base layer is increased again. However, if the barrier layer 4A of the two barrier layers 4A in the superlattice layer 4, which is closer to the base layer 3, is appropriately lowered, the electrons will be reduced. Since the barrier layer 4A on the side closer to the emitter layer 5 is directly tunneled, a collector current of a certain finite value can flow.

Figure 5 shows the base structure in RHET as explained above.
Emitter voltage ■, and collector current ■.

4(A) to (C) are diagrams explaining the relationship between
), and the same symbols as those used in FIGS. 3 and 4 indicate the same parts or have the same meanings.

In the figure, the horizontal axis represents the base-emitter voltage ■. Also,
The collector current 1c is plotted on the vertical axis.

As is clear from the figure, ■ in RHET.

The relationship with IC shows a so-called N-shaped differential negative resistance characteristic. Therefore, by utilizing this characteristic, it is possible to easily realize an oscillator that oscillates at a significantly high frequency.

As described above, in the oscillator of the present invention,
An emitter-side potential barrier layer consisting of a superlattice layer (for example, superlattice layer 4) formed between an emitter layer (for example, n+ type GaAs emitter layer 5) and a base layer (for example, n+ type GaAs base layer 3), and a base layer. A collector-side potential barrier layer (eg, AI) formed between the layer and the collector layer (eg, n+ type GaAs collector layer 1).

Ga, -, As collector side potential barrier layer 2)
a resonant circuit (for example, a resonant circuit RC) connected between the emitter and base of the semiconductor device, and an output terminal (for example, a resonant circuit RC) derived from the collector side of the semiconductor device from which an oscillation current is extracted. For example, the configuration includes an output terminal (OT).

[Effect]

According to the above configuration, the resonant tunneling effect generated in the semiconductor device, which is an oscillation active element, can sufficiently cope with terahertz band oscillation, and the oscillation circuit and output circuit are separated. Therefore, such high frequency oscillation can be stably continued for a long time.

〔Example〕

FIG. 1 shows an explanatory diagram of the main part circuit of one embodiment of the present invention, and FIG.
The same symbols as those used in FIGS. 5 to 5 indicate the same parts or have the same meanings.

In the figure, Q is the semiconductor device which is the oscillating active element explained in FIGS. 3 to 5, RC is the resonant circuit (tank circuit), RL is the load resistance, and 1 is the differential operation area of the semiconductor device Q. A power supply for applying a voltage between the base and emitter in order to set the negative resistance region, and 2 indicate a power supply for applying a voltage between the collector and emitter, respectively. still,
The voltage applied between the base and emitter may be a pulse voltage.

In this oscillator, as mentioned above, a voltage is applied between the collector and emitter from the power supply v1, and
When the operating region of the semiconductor device Q is set to the differential negative resistance region with a voltage applied from Make it.

Since this oscillator has a common base circuit, the input impedance is small but the output impedance is large, the oscillation conditions are determined without being affected by the output circuit, and there is an advantage that the voltage can be amplified. As described above, when a pulse voltage is applied between the base and emitter, oscillation occurs only when a pulse is input, and it can be used as an intermittent oscillator.

〔Effect of the invention〕

In the oscillator according to the present invention, an emitter-side potential barrier layer consisting of a superlattice layer formed between an emitter layer and a base layer, and a collector-side potential barrier layer formed between a base layer and a collector layer. A configuration comprising a semiconductor device having a layer, a resonant circuit connected between an emitter and a base of the semiconductor device, and an output terminal from which an oscillation current is extracted from a collector layer of the semiconductor device. are taken.

According to this configuration, in a semiconductor device that is a RHET, its resonant tunneling effect is sufficiently maintained even in the terahertz band, and since it is a three-terminal device, the oscillation circuit and output circuit are It is completely separated, the oscillation conditions are determined without being affected by the output circuit, and stable oscillation can be maintained even in high frequency bands such as the terahertz band.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of the main part circuit of one embodiment of the present invention, Fig. 2 is an explanatory diagram of the main part circuit of the conventional example, and Figs. 3 (A) and (B) are R
A cutaway side view of the main part of the HET and an energy band diagram. Figures 4 (A) to (C) are energy band diagrams for explaining the operation of the RHET. Figure 5 is the voltage between the base and emitter of the RHET. Each shows a diagram for explaining the relationship between the collector current and the collector current. In the figure, Q is the RHET, RC is the resonant circuit, RL is the load resistance, ■, is the power supply for supplying voltage between the base and emitter of the RHET, and ■2 is the voltage that is supplied between the collector and emitter of the RHET. The power supply and OT for this purpose each indicate the output end. Patent Applicant: Fujitsu Ltd. Representative Patent Attorney: Akira Aitani Representative Patent Attorney: Hiroshi Watanabe Figure 1: Explanatory diagram of the essential circuit of the embodiment Figure 1: Explanatory diagram of the essential circuit of the conventional example Figure 2: Explains the operation of RHET Energy panning diagram Figure 4 for

Claims (1)

[Claims] It has an emitter-side potential barrier layer made of a superlattice layer formed between an emitter layer and a base layer, and a collector-side potential barrier layer formed between a base layer and a collector layer. A semiconductor device comprising: a resonant circuit connected between an emitter and a base of the semiconductor device; and an output terminal from which an oscillation current is extracted from a collector layer of the semiconductor device. oscillator.