JPH0535716B2 - - Google Patents
Info
- Publication number
- JPH0535716B2 JPH0535716B2 JP223987A JP223987A JPH0535716B2 JP H0535716 B2 JPH0535716 B2 JP H0535716B2 JP 223987 A JP223987 A JP 223987A JP 223987 A JP223987 A JP 223987A JP H0535716 B2 JPH0535716 B2 JP H0535716B2
- Authority
- JP
- Japan
- Prior art keywords
- crystal
- molecular beam
- substrate
- growth
- crystal growth
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 239000013078 crystal Substances 0.000 claims description 32
- 239000000758 substrate Substances 0.000 claims description 23
- 239000004065 semiconductor Substances 0.000 claims description 9
- 150000001875 compounds Chemical class 0.000 claims description 7
- 238000000034 method Methods 0.000 claims description 5
- 238000002109 crystal growth method Methods 0.000 claims description 3
- 239000010409 thin film Substances 0.000 claims description 2
- 239000003990 capacitor Substances 0.000 description 7
- 229910001218 Gallium arsenide Inorganic materials 0.000 description 3
- 238000007796 conventional method Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000000151 deposition Methods 0.000 description 2
- 230000008021 deposition Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000001451 molecular beam epitaxy Methods 0.000 description 2
- 230000007935 neutral effect Effects 0.000 description 2
- 230000000737 periodic effect Effects 0.000 description 2
- 230000002123 temporal effect Effects 0.000 description 2
- 229910000980 Aluminium gallium arsenide Inorganic materials 0.000 description 1
- 229910000530 Gallium indium arsenide Inorganic materials 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000001939 inductive effect Effects 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 230000001360 synchronised effect Effects 0.000 description 1
Description
【発明の詳細な説明】
（産業上の利用分野）
本発明は光デバイスないし電子デバイスに応用
可能な化合物半導体の分子線結晶成長方法に関す
る。DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for growing compound semiconductor molecular beam crystals that can be applied to optical devices or electronic devices.
（従来技術とその問題点）
化合物半導体のエピタキシヤル成長方法とし
て、超高真空中で半導体原料物質を加熱蒸発さ
せ、分子線の形態で基板結晶上に照射することに
より成長層を得る分子線エピタキシー法（MBE
法）が広く行われている。通常基板結晶は分子線
源に相対して設けられた加熱可能な保持具上に保
持され、基板結晶の電気的中性が保たれた状態で
結晶成長が行われる。この際成長層厚の制御は一
定強度の分子線に対して成長時間を制御すること
により行う。(Prior art and its problems) As a method for epitaxial growth of compound semiconductors, molecular beam epitaxy is used to heat and evaporate a semiconductor raw material in an ultra-high vacuum and irradiate it onto a substrate crystal in the form of a molecular beam to obtain a grown layer. Law (MBE
law) is widely practiced. Usually, the substrate crystal is held on a heatable holder provided opposite to the molecular beam source, and crystal growth is performed while the substrate crystal is kept electrically neutral. At this time, the growth layer thickness is controlled by controlling the growth time for a molecular beam of constant intensity.
（発明が解決しようとする問題点）
しかしこのような方法では、分子線強度の時間
的ゆらぎが生じた場合には、成長時間を一定に制
御しても成長層厚は所期の目的値からずれてしま
うことになる。このような事態は超薄膜とくに単
原子層数を限定した結晶成長層を得ようとする場
合にはなはだ都合が悪い。従つて分子線強度の多
少のゆらぎが生じても単原子層数が精密に制御し
うる結晶成長方法が望まれる。(Problem to be solved by the invention) However, in such a method, if temporal fluctuations occur in the molecular beam intensity, the grown layer thickness may deviate from the intended target value even if the growth time is kept constant. It will shift. This situation is very inconvenient when trying to obtain an ultra-thin film, especially a crystal growth layer with a limited number of monoatomic layers. Therefore, a crystal growth method is desired in which the number of monoatomic layers can be precisely controlled even if the molecular beam intensity fluctuates to some extent.
本発明は、上に述べた化合物半導体の分子線結
晶成長において成長層厚を原子層単位で制御でき
る結晶成長方法を提供する。 The present invention provides a crystal growth method in which the growth layer thickness can be controlled in units of atomic layers in the above-described molecular beam crystal growth of compound semiconductors.
（問題点を解決するための具体的手段）
本発明によれば、結晶成長に際して基板結晶を
正負に交互に帯電させることにより、この交番電
荷に同期して単原子層成長を行うことが出来、上
記の目的を達成することが出来る。(Specific means for solving the problem) According to the present invention, by alternately charging the substrate crystal positively and negatively during crystal growth, monoatomic layer growth can be performed in synchronization with this alternating charge, The above objectives can be achieved.
（発明の作用・原理）
本発明は、基板結晶の帯電状態により例えば
−化合物半導体を構成する族または族元素
の分子の基板上への付着率が大きく異なるため
に、正負の帯電状態の周期的変化に同期して族
および族元素分子が選択的に基板表面上に付着
するという原理に基づいている。従来の方法では
基板は電気的中性が保たれていたために、各元素
の分子の付着率はそれぞれ常に一定であり時間的
な選択性は生じなかつた。すなわち通常は高蒸気
圧成分の族元素の分子線強度が過剰な雰囲気で
族元素に対してはほとんど100％近い付着率と
なる条件の下で成長が行われている。このとき
族原子は基板表面上に付着すると族原子に比べ
て電気陰性度が小さいために電荷移動により正の
有効電荷を帯びて結晶格子内に取り込まれる。
族原子についてはこの逆である。ところが本発明
において、基板を正に帯電させた場合には、族
原子は表面に付着し電荷移動を生ずると正電荷同
士の電気的反発を受けることになり結晶格子に取
り込まれることが出来ず結局付着率を低下させる
ことになる。このとき族原子については電荷移
動により負の有効電荷を得るので正負電荷の電気
的吸引力により付着率が増大することになる。基
板を負に帯電させた場合には上記の逆で族原子
の付着率が増大し、族原子の付着率が低下す
る。帯電状態の電荷密度を十分大きくすれば、低
い方の付着率はほとんどゼロにまで下げられるの
で、正負の帯電状態の周期的変化に同期した族
および族元素の選択的付着が可能である。結晶
格子へは−原子の対になつて取り込まれ結晶
成長が進行するので、一度に付着した原子層は単
原子層だけが有効であり、一原子層毎の成長が帯
電状態の周期的変化に同期して生じることにな
る。(Operation/Principle of the Invention) The present invention is advantageous in that the adhesion rate of, for example, group or group element molecules constituting a compound semiconductor to the substrate varies greatly depending on the charged state of the substrate crystal. It is based on the principle that group and group element molecules selectively adhere to the substrate surface in synchronization with changes. In the conventional method, since the substrate was kept electrically neutral, the adhesion rate of molecules of each element was always constant, and no temporal selectivity occurred. That is, growth is normally performed in an atmosphere where the molecular beam intensity of the group element, which is a high vapor pressure component, is excessive, and under conditions where the deposition rate for the group element is almost 100%. At this time, when the group atoms adhere to the surface of the substrate, they are incorporated into the crystal lattice with a positive effective charge due to charge transfer because they have lower electronegativity than the group atoms.
The opposite is true for group atoms. However, in the present invention, when the substrate is positively charged, the group atoms adhere to the surface and cause charge transfer, and are subject to electrical repulsion between positive charges and cannot be incorporated into the crystal lattice. This will reduce the adhesion rate. At this time, since the group atoms obtain negative effective charges through charge transfer, the adhesion rate increases due to the electrical attractive force of positive and negative charges. When the substrate is negatively charged, the rate of attachment of group atoms increases and the rate of attachment of group atoms decreases, contrary to the above. If the charge density of the charged state is made sufficiently large, the lower deposition rate can be reduced to almost zero, making it possible to selectively deposit groups and group elements in synchronization with periodic changes in the positive and negative charged states. Atoms are incorporated into the crystal lattice as pairs and crystal growth progresses, so only a single atomic layer is effective for the atomic layer deposited at a time, and the growth of each atomic layer is caused by periodic changes in the charged state. They will occur synchronously.
（実施例）
以下本発明の有利な特性を用いた実施例につい
て説明する。(Example) Examples using the advantageous characteristics of the present invention will be described below.
第１図は本発明の実施例におけ分子線結晶成長
装置の構成の概略を示している。GaAsまたは
InPなどの化合物半導体からなる基板結晶１が
Moなどの導電性材質から成る基板保持具２上に
電気的接触を保つて固定されている。基板保持具
２は超高真空容器３の外部に置かれた蓄電器４の
一方の電極に電気的に接続されている他は、他の
部分と電気的に絶縁されている。基板加熱ヒータ
５、分子線源６，６′，６″の配置や使用について
は通常の分子線結晶成長法と変わらない。結晶成
長に際しては、蓄電器４の他方の電極に接続され
た交流電荷発生器７に交流電荷を発生させ、これ
により蓄電器に正負電荷を交互に誘起する。この
とき基板結晶１には、基板結晶に接続している蓄
電器の極板上とは符号が逆で絶対値のほぼ等しい
電荷が誘起され帯電する。 FIG. 1 schematically shows the configuration of a molecular beam crystal growth apparatus in an embodiment of the present invention. GaAs or
A substrate crystal 1 made of a compound semiconductor such as InP is
It is fixed on a substrate holder 2 made of a conductive material such as Mo while maintaining electrical contact. The substrate holder 2 is electrically insulated from other parts except for being electrically connected to one electrode of a capacitor 4 placed outside the ultra-high vacuum container 3. The arrangement and use of the substrate heater 5 and the molecular beam sources 6, 6', and 6'' are the same as in normal molecular beam crystal growth. During crystal growth, an AC charge generator connected to the other electrode of the capacitor 4 is used. AC charge is generated in the capacitor 7, thereby alternately inducing positive and negative charges in the capacitor.At this time, the substrate crystal 1 has an electric charge of opposite sign and absolute value on the electrode plate of the capacitor connected to the substrate crystal. Almost equal charges are induced and charged.
本実施例では容量１ｍＦの蓄電器を用い、蓄電
器の両極間電圧を実効値1kVとなるように交流的
充電を繰り返した。この場合１クーロンの電荷を
発生することになり、これにより20×20mm2の表面
を有する基板結晶表面上に実効値10-3〜10-2クー
ロン／cm2の面密度で交流的表面電荷を生じさせる
ことが出来た。電荷の交番周期は0.3〜0.5秒とし
た。この交流的帯電処理と併せて通常の方法で分
子線結晶成長を行つた。 In this example, a capacitor with a capacity of 1 mF was used, and alternating current charging was repeated so that the voltage between the electrodes of the capacitor became an effective value of 1 kV. In this case, a charge of 1 coulomb is generated, which causes an alternating current surface charge to be generated on the substrate crystal surface having a surface of 20 x 20 mm 2 with an effective value of 10 -3 to 10 -2 coulomb/cm 2 . I was able to make it happen. The alternating period of charge was set to 0.3 to 0.5 seconds. In addition to this alternating current charging treatment, molecular beam crystal growth was performed using a conventional method.
第２図は上記の方法でGaAsを成長させた場合
の層厚の制御性を従来法と比較して示したもので
ある。層厚の設定値に対するバラツキが格段に改
善されていることが明らかである。同様の効果は
GaAs以外の化合物半導体とくにAlGaAs、
InGaAsなどの混晶半導体についてもみられた。 FIG. 2 shows the controllability of the layer thickness when GaAs is grown by the above method in comparison with the conventional method. It is clear that the variation in layer thickness with respect to the set value has been significantly improved. A similar effect is
Compound semiconductors other than GaAs, especially AlGaAs,
This phenomenon was also observed in mixed crystal semiconductors such as InGaAs.
（発明の効果）
以上説明したように、分子線結晶成長におい
て、基板結晶を正負に交互に帯電させながら結晶
成長を行うことにより、帯電周期に同期した単原
子層成長が可能となり、成長層厚の制御性が大幅
に向上する。(Effects of the Invention) As explained above, in molecular beam crystal growth, by performing crystal growth while alternately charging the substrate crystal positively and negatively, monoatomic layer growth synchronized with the charging cycle becomes possible, and the growth layer thickness increases. controllability is greatly improved.
第１図は本発明の実施例における分子線結晶成
長装置の構成を示す図、第２図は本発明の効果を
示す図である。
図において、１…基板結晶、２…基板保持具、
３…超高真空容器、４…蓄電器、５…加熱ヒー
タ、６，６′，６″…分子線源、７…交流電荷発生
器。
FIG. 1 is a diagram showing the configuration of a molecular beam crystal growth apparatus in an embodiment of the present invention, and FIG. 2 is a diagram showing the effects of the present invention. In the figure, 1...substrate crystal, 2...substrate holder,
3...Ultra-high vacuum container, 4...Electric condenser, 5...Heater, 6, 6', 6''...Molecular beam source, 7...AC charge generator.
Claims (1)
薄膜を形成する分子線結晶成長方法において基板
結晶を正負に交互に帯電させながら結晶成長を行
うことを特徴とする化合物半導体の分子線結晶成
長方法。1 Molecular beam crystal growth of a compound semiconductor characterized by performing crystal growth while alternately charging the substrate crystal positively and negatively in a molecular beam crystal growth method in which a thin film is formed on a substrate crystal by molecular beam irradiation in an ultra-high vacuum. Method.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP223987A JPS63170299A (en) | 1987-01-07 | 1987-01-07 | Molecular ray crystal growth method for compound semiconductor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP223987A JPS63170299A (en) | 1987-01-07 | 1987-01-07 | Molecular ray crystal growth method for compound semiconductor |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS63170299A JPS63170299A (en) | 1988-07-14 |
| JPH0535716B2 true JPH0535716B2 (en) | 1993-05-27 |
Family
ID=11523805
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP223987A Granted JPS63170299A (en) | 1987-01-07 | 1987-01-07 | Molecular ray crystal growth method for compound semiconductor |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS63170299A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2501118B2 (en) * | 1988-06-17 | 1996-05-29 | 忠弘 大見 | Method for manufacturing semiconductor device |
-
1987
- 1987-01-07 JP JP223987A patent/JPS63170299A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS63170299A (en) | 1988-07-14 |
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