JPH01157416A - Method for manufacturing zinc sulfide thin film - Google Patents

Abstract

PURPOSE:To uniformly form zinc sulfide thin film having good quality and little lattice defect, by alternately irradiating a substrate with zinc molecular beam obtd. by evaporating metal zinc by heating, and sulfur molecular beam obtd. by thermally decomposing the gas of compd. contg. sulfur. CONSTITUTION:The surface of the substrate 4 is alternately irradiated in a vacuum (vessel 1) with the zinc molecular beam 9b and the sulfur molecular beam 10b obtd. by thermally decomposing (heater 8) the gas 11 of the compd. contg. sulfur. As the compd. contg. sulfur, hydrogen sulfide, dimethyl sulfide or diethyl sulfide can be used. As the substrate material, the single crystal having crystal structure same or similar to one of zinc sulfide, such as gallium arsenide, gallium phosphide, silicon is pref. The temp. of the substrate during the formation of thin film is preferably in the range of 250-500 deg.C.

Description

Translated fromJapanese

【発明の詳細な説明】産業上の利用分野本発明は発光ダイオード等の発光素子に用いられる半導
体薄膜材料の製造方法に関し、特に青色発光素子用材料
として良好な特性を示す硫化亜鉛薄膜の製造方法に関す
るものである。DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for manufacturing a semiconductor thin film material used for light emitting devices such as light emitting diodes, and in particular a method for manufacturing a zinc sulfide thin film that exhibits good properties as a material for blue light emitting devices. It is related to.

従来の技術従来、硫化亜鉛薄膜を製造する方法として、第２図に示
すような真空蒸着装置を用い、真空容器１内でルツボ３
内に装填した硫化亜鉛原料３ａを加熱蒸発させ、基板４
の表面に硫化亜鉛薄膜５を形成するものが知られている
。2. Description of the Related Art Conventionally, as a method for producing a zinc sulfide thin film, a vacuum evaporation apparatus as shown in FIG.
The zinc sulfide raw material 3a loaded in the substrate is heated and evaporated, and the substrate 4 is heated and evaporated.
It is known that a zinc sulfide thin film 5 is formed on the surface of the metal.

発明が解決しようとする問題点しかしながら上述のような従来の方法では、亜鉛と硫黄
の原子または分子が同時に基板面に飛来するため、膜形
成の初期において、基板面上の結晶成長のおこシやすい
位置に集中して結晶が成長し、いわゆる島状成長の状態
となる。この場合、得られた膜は結晶粒の集合体となる
ため、結晶粒界に格子欠陥が多数発生し、発光素子材料
として充分な特性が得られないという問題点があった。Problems to be Solved by the Invention However, in the conventional method as described above, since zinc and sulfur atoms or molecules simultaneously fly onto the substrate surface, crystal growth tends to occur on the substrate surface in the early stage of film formation. Crystals grow concentrated in certain positions, resulting in a state of so-called island-like growth. In this case, since the obtained film becomes an aggregate of crystal grains, a large number of lattice defects occur at the crystal grain boundaries, resulting in the problem that sufficient characteristics as a light emitting device material cannot be obtained.

またこの場合、膜面の凹凸や膜厚分布が大きくなるとい
う問題点もあった。Further, in this case, there was also a problem that the unevenness of the film surface and the film thickness distribution became large.

問題点を解決するための手段本発明は上記問題点を解決するため、金属亜鉛を加熱蒸
発させて得た亜鉛分子線と硫黄を含む化合物のガスを熱
分解させて得た硫黄分子線を交互に基板に照射するもの
である。Means for Solving the Problems In order to solve the above-mentioned problems, the present invention alternates between zinc molecular beams obtained by heating and evaporating metal zinc and sulfur molecular beams obtained by thermally decomposing gas of a sulfur-containing compound. It irradiates the substrate at the same time.

作用本発明は上記の手段により、亜鉛と硫黄の原子層を一層
ずつ交互に形成し、その結果、膜形成の初期よシ均一な
二次元的な結晶成長が生じるという作用にもとづくもの
である。Operation The present invention is based on the operation that atomic layers of zinc and sulfur are alternately formed layer by layer by the above-mentioned means, and as a result, uniform two-dimensional crystal growth occurs from the initial stage of film formation.

実施例以下、本発明を実施例により詳細に説明する。ExampleHereinafter, the present invention will be explained in detail with reference to Examples.

第１図は本発明の製造方法の一実施例で用いられる分子
線エピタキシー装置の構造を示す概略図である。同図に
おいて、９は通常の蒸発用ルツボで、原料となる金属亜
鉛９＆を装填しておき、ヒーター７によシ加熱蒸発させ
て亜鉛分子線９ｂを得る。また１ｏはガス分解セルで、
硫化水素ガス容器１１から導入されたガスをヒーター８
により加熱分解させて、硫黄分子線１０ｂを得る。ここ
で硫黄分子線の原料に硫化水素ガスを用いる理由は、単
体の硫黄（固体）は室温でもかなり高い蒸気圧を有する
ため、高真空を得るのに不可欠な真空容器１の加熱脱ガ
ス処理の過程で蒸発してしまうので実用的でないことに
なる。FIG. 1 is a schematic diagram showing the structure of a molecular beam epitaxy apparatus used in an embodiment of the manufacturing method of the present invention. In the figure, reference numeral 9 denotes a normal evaporation crucible, which is loaded with metal zinc 9& as a raw material, heated and evaporated by a heater 7 to obtain zinc molecular beams 9b. Also, 1o is a gas decomposition cell,
The gas introduced from the hydrogen sulfide gas container 11 is transferred to the heater 8
The sulfur molecular beam 10b is obtained by thermal decomposition. The reason why hydrogen sulfide gas is used as the raw material for the sulfur molecular beam is that elemental sulfur (solid) has a fairly high vapor pressure even at room temperature. It evaporates during the process, making it impractical.

実際の薄膜成長は次のような手順で行なう。まず表面を
清浄にした基板４を基板ホルダ６に装着する。基板材料
としては硫化亜鉛と同じか又は類似の結晶構造を有し格
子定数の近いガリウム砒素。Actual thin film growth is performed in the following steps. First, the substrate 4 whose surface has been cleaned is mounted on the substrate holder 6. The substrate material is gallium arsenide, which has the same or similar crystal structure and similar lattice constant to zinc sulfide.

ガリウム燐、シリコンなどの単結晶が好適である。Single crystals such as gallium phosphide and silicon are suitable.

次に真空容器１を１　ｏ−９Ｔｏｒｒ以下程度の超高真
空まで排気する。その後、ルツボ９を例えば４００°Ｃ
程度に加熱し、適切な強度の亜鉛分子線９ｂが　　　　
−得られるようにする。またガス分解セル１０を加熱す
るとともに、流量調節弁１２を開いて硫化水素ガスを流
し、適切な強度の硫黄分子線１０ｂが得られるようにす
る。ガス分解セルの温度は、′７ｏ。Next, the vacuum container 1 is evacuated to an ultra-high vacuum of about 1 o-9 Torr or less. After that, the crucible 9 is heated to, for example, 400°C.
Zinc molecular beam 9b of appropriate strength is heated to a certain degree.
- Make it possible to obtain. In addition, while heating the gas decomposition cell 10, the flow control valve 12 is opened to allow hydrogen sulfide gas to flow, so that a sulfur molecular beam 10b of appropriate strength can be obtained. The temperature of the gas decomposition cell is '7o.

℃以−上あれば硫化水素ガスをほぼ完全に分解すること
ができる。℃ or higher, hydrogen sulfide gas can be almost completely decomposed.

次に基板４を約６００　℃に加熱して表面を更に清浄化
する。その後、基板を結晶成長に適切な温度まで下げる
。この場合には例えば３００°Ｃとする。この後、シャ
ッター１３及び１４を交互に開き、結晶成長を行う。す
なわち、例えばまずシャッター１３を開いて亜鉛分子線
９ｂを基板に照射すると亜鉛原子層が一層だけ形成され
る。その後シャッター１３を閉じ、シャッター１４を開
いて、硫黄分子線１０ｂを照射すると、硫黄原子層が一
層だけ形成される。この操作をくシ返すと、シャッター
の開閉回数に比例した膜厚の硫化亜鉛薄膜を均一に形成
することができる。シャッターを開いておく時間は、一
原子層が形成されるのに充分。Next, the substrate 4 is heated to about 600° C. to further clean the surface. The substrate is then lowered to a temperature suitable for crystal growth. In this case, the temperature is, for example, 300°C. After this, the shutters 13 and 14 are opened alternately to perform crystal growth. That is, for example, when the shutter 13 is first opened and the substrate is irradiated with the zinc molecular beam 9b, only one layer of zinc atoms is formed. Thereafter, when the shutter 13 is closed, the shutter 14 is opened, and the sulfur molecular beam 10b is irradiated, only one layer of sulfur atoms is formed. By repeating this operation, it is possible to uniformly form a zinc sulfide thin film with a thickness proportional to the number of times the shutter is opened and closed. The shutter is left open long enough for a single atomic layer to form.

な時間以上であれば特に制限はない。これは亜鉛および
硫黄の蒸気圧が上述の基板温度では充分に高いため、原
子層が一層形成されると同種原子、まそれ以上堆積せず
、再蒸発するためである。There is no particular limit as long as it is longer than a certain amount of time. This is because the vapor pressures of zinc and sulfur are sufficiently high at the above-mentioned substrate temperature, so that once an atomic layer is formed, no more atoms of the same type are deposited and are reevaporated.

以上のような方法で形成した硫化亜鉛薄膜は、成長初期
よ）二次元的で均一な／結晶成長をするため、極めて格
子欠陥の少ない良質な単結晶膜となシ、優れた電気的・
光学的性質を示す。Since the zinc sulfide thin film formed by the method described above grows two-dimensionally and uniformly (in the early stages of growth), it becomes a high-quality single crystal film with extremely few lattice defects, and has excellent electrical properties.
Shows optical properties.

なお上述の実施例では硫黄分子線の原料として硫化水素
を用いたが、この他ジメチル硫黄やジエチル硫黄などの
硫黄を含む有機化合物ガスを用いても同様の効果が得ら
れる。In the above embodiment, hydrogen sulfide was used as the raw material for the sulfur molecular beam, but similar effects can be obtained by using other organic compound gases containing sulfur such as dimethyl sulfur and diethyl sulfur.

また、薄膜形成中の基板温度は、２００℃以上５００℃
以下が好適である。２００　℃以下では各原子が正確な
格子位置に安定せず、また５００°Ｃ以上では原子の再
蒸発が過剰になり原子の空孔が生じるので、何れの場合
も完全な結晶が得られなくなるためである。In addition, the substrate temperature during thin film formation is 200°C or more and 500°C.
The following are preferred. Below 200°C, each atom is not stabilized in its correct lattice position, and above 500°C, atoms re-evaporate excessively and create atomic vacancies, making it impossible to obtain a perfect crystal in either case. It is.

発明の効果以上述べてきたように、本発明によれば、格子欠陥の少
ない良質な硫化亜鉛薄膜を均一に形成することができる
。その結果、高効率の青色発光素子が実現でき、実用的
に極めて有用である。Effects of the Invention As described above, according to the present invention, a high quality zinc sulfide thin film with few lattice defects can be uniformly formed. As a result, a highly efficient blue light emitting device can be realized, which is extremely useful in practice.

【図面の簡単な説明】[Brief explanation of the drawing]

第１図は本発明の一実施例で用いられる分子線エピタキ
シー装置の構造を示す概略図、第２図は従来例で用いら
れる蒸着装置の構造を示す概略図である。１・・・・・・真空容器、２・・・・・・真空ポンプ、
３・・・・・・ルツボ、３＆・・・・・・硫化亜鉛原料
、４・・・・・・基板、６・・・・・・硫化亜鉛薄膜、
６・・・・・・基板ホルダ、７．８・・・・・・ヒータ
ー、９・・・・・・ルツボ、９１Ｌ・・・・・・亜鉛、
９ｂ・・・二・・亜鉛分子線、１ｏ・・・・・・ガス分
解セル、１０ｂ・・・・・・硫黄分子線、１１・・・・
・・硫化水素ガス容器、１２・・・・・・流量調節弁、
１３．１４・・・・・・シャッター。FIG. 1 is a schematic diagram showing the structure of a molecular beam epitaxy apparatus used in an embodiment of the present invention, and FIG. 2 is a schematic diagram showing the structure of a vapor deposition apparatus used in a conventional example. 1... Vacuum container, 2... Vacuum pump,
3... Crucible, 3 &... Zinc sulfide raw material, 4... Substrate, 6... Zinc sulfide thin film,
6... Substrate holder, 7.8... Heater, 9... Crucible, 91L... Zinc,
9b...2...Zinc molecular beam, 1o...Gas decomposition cell, 10b...Sulfur molecular beam, 11...
...Hydrogen sulfide gas container, 12...Flow rate control valve,
13.14... Shutter.

Claims (5)

Translated fromJapanese

【特許請求の範囲】[Claims]（１）真空中において、亜鉛分子線と、硫黄を含む化合
物の気体を熱分解して得た硫黄分子線を交互に基板表面
に照射することを特徴とする硫化亜鉛薄膜の製造方法。(1) A method for producing a zinc sulfide thin film, which comprises alternately irradiating a substrate surface with a zinc molecular beam and a sulfur molecular beam obtained by thermally decomposing a gas of a sulfur-containing compound in a vacuum.（２）硫黄を含む化合物を硫化水素またはジメチル硫黄
またはジエチル硫黄とした特許請求の範囲第１項記載の
硫化亜鉛薄膜の製造方法。(2) The method for producing a zinc sulfide thin film according to claim 1, wherein the sulfur-containing compound is hydrogen sulfide, dimethyl sulfur, or diethyl sulfur.（３）硫黄を含む化合物を硫化水素とし、熱分解温度を
７００℃以上とした特許請求の範囲第１項記載の硫化亜
鉛薄膜の製造方法。(3) The method for producing a zinc sulfide thin film according to claim 1, wherein the sulfur-containing compound is hydrogen sulfide, and the thermal decomposition temperature is 700°C or higher.（４）基板をガリウム砒素またはガリウム燐またはシリ
コンのそれぞれ単結晶で構成した特許請求の範囲第１項
から第３項までの何れかに記載の硫化亜鉛薄膜の製造方
法。(4) The method for producing a zinc sulfide thin film according to any one of claims 1 to 3, wherein the substrate is made of a single crystal of gallium arsenide, gallium phosphide, or silicon, respectively.（５）基板温度を２５０℃以上５００℃以下とした特許
請求の範囲第１項から第４項までの何れかに記載の硫化
亜鉛薄膜の製造方法。(5) The method for manufacturing a zinc sulfide thin film according to any one of claims 1 to 4, wherein the substrate temperature is 250°C or more and 500°C or less.