CN102565600A - Method for determining and testing ohmic contact between black silicon material and metal electrode - Google Patents

Abstract

The invention discloses a method for determining and testing ohmic contact between a black silicon material and a metal electrode, belonging to the technical field of semiconductor photoelectronic materials and devices. The invention has the technical schemes that: an I-V characteristic curve of a metal/black silicon material can be directly tested through a three-electrode horizontal test device with a reverse bias voltage, and the contact type between the black silicon material and the metal electrode can be judged; and 2, the ohmic contact of the black silicon material can be tested by using a TLM (Transmission Line Model) method with the reverse bias voltage, thus a specific contact resistance can be obtained. According to the method disclosed by the invention, the influence on the determination and the test for the ohmic contact of the black silicon material due to heterojunction structures of black silicon/monocrystalline silicon in the traditional metal/black silicon/monocrystalline silicon sandwich structure is solved, and the specific contact resistance value of the metal/black silicon can be accurately tested.

Description

Judgment and test method of ohmic contact between black silicon material and metal electrode

technical field

The invention belongs to the technical field of semiconductor optoelectronic materials and devices, in particular to a method for judging and testing ohmic contact between black silicon materials and metal electrodes.

Background technique

Black silicon is a silicon material obtained when the research group of Professor Mazur of Harvard University uses a femtosecond laser to irradiate the surface of a single crystal silicon wafer in a certain gas environment. The surface of the obtained black silicon material contains quasi-regularly arranged micron-scale pyramid structures, and has a high-concentration chalcogen (oxygen) atom doping layer. Experiments have proved that the black silicon material absorbs almost all light with a wavelength of 250-2500nm, and it is extremely sensitive to incident light. Compared with photodetectors based on traditional silicon wafers, the sensitivity of black silicon wafers to light can be increased by 100~ 500 times, and has a good response to near-infrared light. These advantages make black silicon materials have important application value in the fields of silicon photodetectors and solar cells.

In semiconductor science, whether it is the study of semiconductor physics and material properties, or the manufacture of semiconductor devices, there is always a need for contact between metal and semiconductor, which is essential. The contact between metal and semiconductor can be divided into two categories: one is rectifying contact, which has a nonlinear relationship between forward and reverse "current-voltage"; Ohmic contacts with current-voltage characteristics. Due to poor electrical contact will cause a large Schottky barrier height, resulting in a large contact resistance, so that the "current-voltage" characteristics of semiconductor devices are not determined by the resistance of the semiconductor material itself, but by the semiconductor material and the metal electrode The contact type is determined. Usually semiconductor devices and samples used to test semiconductor parameters are required to be connected with ohmic contacts. The quality of ohmic contact and the size of contact resistance directly affect performance indicators such as device efficiency, gain and switching speed.

A very important parameter to measure the quality of ohmic contact is the specific contact resistance ρ _c , which is the key reference in the application of devices. The transmission line model method (TLM method), with its mature theory, convenient test and relatively accurate calculation The specific contact resistance of the metal-semiconductor contact and the surface resistance of the semiconductor have become the commonly used test methods at present, as shown in Figure 1. Firstly, strip-shaped electrodes (such as 1, 2, 3, 4, 5) with different spacings are prepared on the film 8 to be tested, and the length of each electrode is L and the width is W. Then, a current or a voltage is passed between two strip electrodes with different spacing _dn , and the total resistance R _m is obtained, which can be expressed by the following formula:

${\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}}{\mathrm{<span\; class="notranslate">\; W</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

where _R is the resistance of the semiconductor material between the two electrodes, _R is the contact resistance, and _R can be expressed as

${\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}\frac{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}}{\mathrm{<span\; class="notranslate">\; W</span>}}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; coth</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; L</span>}}{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

Therefore, _Rm is

${\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}}{\mathrm{<span\; class="notranslate">\; W</span>}}<span\; class="notranslate">\; +</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}\frac{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}}{\mathrm{<span\; class="notranslate">\; W</span>}}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; coth</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; L</span>}}{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

Among them, ρ _s is the square resistance of the semiconductor thin film material, and L _T is called the transmission length. When L≥1.5L _T , coth(L/L _T ) approaches 1, so

${\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}}{\mathrm{<span\; class="notranslate">\; W</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}}<span\; class="notranslate">\; \&ap;</span>\frac{{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{\mathrm{<span\; class="notranslate">\; W</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; d</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; )</span>$

This is the linear equation of the total resistance R _m changing with the interval length d _n of the measuring electrodes, ρ _s can be obtained from the slope of the straight line, L _T can be obtained from the intercept of the straight line, and then through the relationship

${\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; the\; <figure-callout\; id="2"\; label="s\; L\; T"\; filenames="HDA00001370555200012.png,HDA00001370555200013.png"\; state="\{\{state\}\}">s</figure-callout></span><figure-callout\; id="2"\; label="s\; L\; T"\; filenames="HDA00001370555200012.png,HDA00001370555200013.png"\; state="\{\{state\}\}">\; </figure-callout>}}{\mathrm{<span\; class="notranslate">\; L</span>}}_{}^{}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}^{}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}{\mathrm{<span\; class="notranslate">\; WL</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 5</span>}<span\; class="notranslate">\; )</span>$

The specific contact resistance ρ _c of the ohmic contact of the sample film can be obtained.

However, for the contact between black silicon material and metal, due to its unique metal/black silicon/single crystal silicon sandwich structure, there is black silicon/single crystal silicon heterojunction, which makes it difficult to test black silicon with conventional transmission line model method. There are certain difficulties in determining the specific contact resistance ρ _c between the silicon material and the metal electrode, and even the contact type between the black silicon material and the metal electrode is difficult to judge.

Contents of the invention

The invention provides a method for judging and testing ohmic contact between a black silicon material and a metal electrode to solve the problem that the I-V characteristics of the metal/black silicon material cannot be directly tested due to the existence of black silicon/single crystal silicon heterogeneity . The method can effectively determine the contact type between the black silicon material and the metal electrode, accurately test the ohmic contact of the black silicon material, and calculate the specific contact resistance of the metal/black silicon more accurately.

Technical scheme of the present invention is:

The method for judging and testing the ohmic contact between the black silicon material and the metal electrode comprises the following steps:

Step 1: As shown in Figure 2, deposit three square metal electrodes 1-3 with the same size and equal spacing on the surface of the black silicon material 8, and deposit a metal counter electrode 10 on the back of the monocrystalline silicon 9 in contact with the black silicon material 8 ;

Step 2: Apply a forward voltage bias U ₊ between any two adjacent square metal electrodes on the surface of the black silicon material 8 with the semiconductor parameter tester 12; A reverse voltage bias U ₋ is applied between a square metal electrode and the metal counter electrode 10;

Step 3: Gradually increase the size of the reverse voltage bias U _- , and it can be observed that with the increase of the reverse voltage bias U _- , the two square metal electrodes on the surface of the black silicon material 8 corresponding to the forward voltage bias U ₊ The current between gradually decreases, and finally reaches a stable value; at this time, the black silicon/single crystal silicon heterojunction is completely reverse biased, and the reverse voltage value at this time is the complete reverse bias voltage value; record the semiconductor parameters at this time The voltage, current value and full reverse bias voltage value of the tester 12;

Step 4: As described in step 2, the reverse voltage bias _U- is not lower than the full reverse bias voltage value described in step 3, that is, under the condition that the black silicon/single crystal silicon heterojunction is completely reverse biased, change The magnitude of the forward voltage bias U ₊ as described in step 2, and record the current values of any two adjacent square metal electrodes on the surface of the black silicon material 8 under different forward voltage bias U ₊ ;

Step 5: According to the current values of any two adjacent square metal electrodes on the surface of the black silicon material 8 recorded in step 4 under different forward voltage bias U ₊ , the IV characteristic curve of metal/black silicon is obtained and according to the IV characteristic The curve determines the contact type between the black silicon material and the metal electrode: if the IV characteristic curve of the metal/black silicon is a straight line, the contact type between the black silicon material and the metal electrode is an ohmic contact; if the IV characteristic curve of the metal/black silicon If the curve is a curve, the contact type between the black silicon material and the metal electrode is a rectifying contact.

The test method of the specific contact resistance between the black silicon material of ohmic contact and metal electrode, comprises the following steps:

Step 1: As shown in Figure 3, deposit six strip-shaped metal electrodes 1-6 with the same size and successively increasing spacing on the surface of the black silicon material 8, and deposit metal on the back of the single crystal silicon 9 in contact with the black silicon material 8 counter electrode 10;

Step 2: Apply a reverse voltage bias U ₋ between the first strip-shaped metal electrode 1 and the metal counter electrode 10 on the surface of the black silicon material 8 with a variable voltage source; 8. Apply a forward voltage bias U ₊ between any two adjacent strip-shaped metal electrodes remaining on the surface;

Step 3: Gradually increase the size of the reverse voltage bias U _- , and it can be observed that with the increase of the reverse voltage bias U _- , any two remaining strips on the surface of the black silicon material 8 corresponding to the forward voltage bias U ₊ The current between the shaped metal electrodes gradually decreases, and finally reaches a stable value; at this time, the black silicon/single crystal silicon heterojunction is completely reverse-biased, and the reverse voltage value at this time is the fully reverse-biased voltage value;

Step 4: As described in step 2, the reverse voltage bias _U- is not lower than the complete reverse bias voltage value described in step 3, that is, under the condition that the black silicon/single crystal silicon heterojunction is completely reverse biased, use The semiconductor parameter tester 12 applies a constant forward voltage bias between any two strip-shaped metal electrodes with different spacings remaining on the surface of the black silicon material 8, and measures the current intensity, thereby obtaining the total value between the electrodes with different spacings. Resistance R _m ;

Step 5: Make a straight line of the functional relationship between the total resistance R _m and different electrode spacing d _n , according to the calculation formula (4) in the transmission line model method

${\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}}{\mathrm{<span\; class="notranslate">\; W</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}}<span\; class="notranslate">\; \&ap;</span>\frac{{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{\mathrm{<span\; class="notranslate">\; W</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; d</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; )</span>$

As can be seen, ρ _s can be obtained by the slope of the straight line of the function relation, and _LT can be obtained by the intercept of the straight line of the function relation, and then by formula (5)

${\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; the\; <figure-callout\; id="2"\; label="s\; L\; T"\; filenames="HDA00001370555200012.png,HDA00001370555200013.png"\; state="\{\{state\}\}">s</figure-callout></span><figure-callout\; id="2"\; label="s\; L\; T"\; filenames="HDA00001370555200012.png,HDA00001370555200013.png"\; state="\{\{state\}\}">\; </figure-callout>}}{\mathrm{<span\; class="notranslate">\; L</span>}}_{}^{}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}^{}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}\mathrm{<span\; class="notranslate">\; W</span>}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 5</span>}<span\; class="notranslate">\; )</span>$

The specific contact resistance ρ _c between the black silicon material in ohmic contact and the metal electrode is obtained.

The method for judging and testing the ohmic contact between the black silicon material and the metal electrode provided by the present invention, under the condition that the black silicon/single crystal silicon heterojunction is fully reversed biased, by testing the I-V characteristic curve of the metal/black silicon material, It realizes the effective determination of the contact type between black silicon material and metal electrode and the accurate test of the ohmic contact of black silicon material, and calculates the specific contact resistance of metal/black silicon more accurately, and the experimental process is simple and easy to operate .

Description of drawings

Figure 1 is a schematic plan view of a sample tested using the transmission line model method. 1, 2, 3, 4, and 5 in the figure are strip electrodes with different spacings, and 8 is the sample film to be tested.

Fig. 2 is a schematic cross-sectional structure diagram of a three-electrode transverse testing device with reverse voltage bias. In the figure, 1, 2, and 3 are metal electrodes, 8 is black silicon material, 9 is monocrystalline silicon, 10 is a metal back electrode, 11 is a variable voltage source, and 12 is a semiconductor parameter tester.

Fig. 3 is a schematic diagram of the principle of testing black silicon samples by the transmission line model method with reverse voltage bias. 1, 2, 3, 4, 5, and 6 in the figure are strip electrodes with different pitches, 8 is black silicon material, 9 is monocrystalline silicon, and 10 is a metal back electrode.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

The method for judging and testing the ohmic contact between the black silicon material and the metal electrode comprises the following steps:

Step 1: As shown in FIG. 2 , prepare three square Al/Ni electrodes 1 , 2 , 3 on the surface of the black silicon material 8 with a size of 2.0mm×2.0mm and a spacing of 2.0mm. An Al electrode 10 is deposited on the back of the crystalline silicon 9, and the size of the electrode is 10.0 mm×10.0 mm.

Step 2: Using the semiconductor parameter tester 12, apply a forward voltage bias of 2V between the electrodes 2 and 3, and test the current intensity between the two electrodes.

Step 3: Use a variable voltage source to apply a reverse voltage bias between electrodes 1 and 10, and gradually increase the voltage value. It can be observed that as the reverse voltage increases, the current between electrodes 2 and 3 gradually increases. decreases and finally reaches a stable value. At this time, read out the current and voltage values in the semiconductor parameter tester. At this time, the black silicon/single crystal silicon heterojunction is completely reverse biased, and the reverse voltage value at this time is the complete reverse bias voltage value, and the current value between electrodes 2 and 3 is the current value between metal/black silicon.

Step 4: Under the condition of ensuring that the black silicon/single crystal silicon heterojunction is fully reverse biased, use a semiconductor parameter tester to measure the current intensity between electrodes 2 and 3 under continuous forward voltage bias in the range of -2 to 2V , get the I-V characteristic curve of metal/black silicon and determine the contact type between the black silicon material and the metal electrode according to the I-V characteristic curve.

The test method of the specific contact resistance between the black silicon material of ohmic contact and metal electrode, comprises the following steps:

Step 1: As shown in Figure 3, prepare six strip-shaped Al/Ni electrodes 1, 2, 3, 4, 5, 6 on the surface of the black silicon material 8 according to the transmission line model pattern, the electrode size is 0.5×1.5mm, and The pitches are: 0.2mm, 0.4mm, 0.8mm, 1.4mm and 2.0mm. An Al electrode 10 is deposited on the back of the single crystal silicon 9, and the size of the electrode is 4.0mm×4.0mm.

Step 2: Apply a reverse voltage bias U ₋ between the first strip-shaped metal electrode 1 and the metal counter electrode 10 on the surface of the black silicon material 8 with a variable voltage source; 8. Apply a forward voltage bias U ₊ between any two adjacent strip-shaped metal electrodes remaining on the surface;

Step 3: Gradually increase the size of the reverse voltage bias U _- , and it can be observed that with the increase of the reverse voltage bias U _- , any two remaining strips on the surface of the black silicon material 8 corresponding to the forward voltage bias U ₊ The current between the shaped metal electrodes gradually decreases, and finally reaches a stable value; at this time, the black silicon/single crystal silicon heterojunction is completely reverse-biased, and the reverse voltage value at this time is the fully reverse-biased voltage value;

Step 4: As described in step 2, the reverse voltage bias _U- is not lower than the complete reverse bias voltage value described in step 3, that is, under the condition that the black silicon/single crystal silicon heterojunction is completely reverse biased, use The semiconductor parameter tester 12 applies a constant forward voltage bias of 1V between any two strip-shaped metal electrodes with different spacings remaining on the surface of the black silicon material 8, and measures the current intensity, thereby obtaining the distance between electrodes with different spacings. The total resistance R _m of;

Step 5: Make a straight line of the functional relationship between the total resistance R _m and different electrode spacing d _n , according to the calculation formula in the transmission line model method

${\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}}{\mathrm{<span\; class="notranslate">\; W</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}}<span\; class="notranslate">\; \&ap;</span>\frac{{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}{\mathrm{<span\; class="notranslate">\; W</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; d</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; )</span>$

As can be seen, ρ _s can be obtained by the slope of the functional relationship straight line, and _LT can be obtained by the intercept of the functional relationship straight line, and then by the formula

${\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; the\; <figure-callout\; id="2"\; label="s\; L\; T"\; filenames="HDA00001370555200012.png,HDA00001370555200013.png"\; state="\{\{state\}\}">s</figure-callout></span><figure-callout\; id="2"\; label="s\; L\; T"\; filenames="HDA00001370555200012.png,HDA00001370555200013.png"\; state="\{\{state\}\}">\; </figure-callout>}}{\mathrm{<span\; class="notranslate">\; L</span>}}_{}^{}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}^{}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}{\mathrm{<span\; class="notranslate">\; WL</span>}}_{\mathrm{<span\; class="notranslate">\; T</span>}}$

The specific contact resistance ρ _c between the black silicon material in ohmic contact and the metal electrode is obtained.

The above are only representative examples among numerous specific application scopes of the present invention, and do not constitute any limitation to the protection scope of the present invention. All technical solutions formed by transformation or equivalent replacement fall within the protection scope of the present invention.

Claims (2)

1. the judgement of Ohmic contact and method of testing between black silicon material and the metal electrode may further comprise the steps:

Step 1: the square metal electrode (1～3) identical in three sizes of black silicon material (8) surface deposition, that spacing equates, simultaneously at monocrystalline silicon (9) the backside deposition metal pair electrode (10) that contacts with black silicon material (8);

Step 2: between two adjacent arbitrarily square metal electrodes of black silicon material (8) surface, apply a forward voltage bias U with semiconductor parametric tester (12) ₊Use variable voltage source (11) between the remaining square metal electrode in black silicon material (8) surface and metal pair electrode (10), to apply the reverse voltage U that setovers simultaneously _-

Step 3: increase reverse voltage biasing U gradually _-Size, can observe along with reverse voltage biasing U _-Increase, forward voltage bias U ₊Electric current between corresponding two square metal electrodes in black silicon material (8) surface reduces gradually, and finally reaches a stationary value; This moment, black silicon/monocrystalline silicon heterojunction was partially anti-fully, and the reverse voltage value of this moment is complete reversed bias voltage value; Note voltage, current value and the complete reversed bias voltage value of semiconductor parametric tester this moment (12);

Step 4: at the biasing of reverse voltage described in step 2 U _-Be not less than complete reversed bias voltage value described in the step 3, promptly guarantee under the anti-inclined to one side fully condition of black silicon/monocrystalline silicon heterojunction change forward voltage bias U described in step 2 ₊Size, and arbitrarily adjacent two the square metal electrodes in record black silicon material (8) surface are at different forward voltage bias U ₊Under current value;

Step 5: according to adjacent arbitrarily two the square metal electrodes in black silicon material (8) surface of step 4 record at different forward voltage bias U ₊Under current value; Obtain the I-V family curve of metal/black silicon and judge the contact type between black silicon material and the metal electrode according to this I-V family curve: if the I-V family curve of metal/black silicon is a straight line, then the contact type between black silicon material and the metal electrode is an Ohmic contact; If metal/and the I-V family curve of black silicon is a curve, then black silicon material is that rectification contacts with contact type between the metal electrode.

2. the method for testing of the black silicon material of Ohmic contact and the specific contact resistivity between the metal electrode may further comprise the steps:

Step 1: at six of black silicon material (8) the surface depositions bullion electrode (1～6) that size is identical, spacing increases successively, simultaneously at monocrystalline silicon (9) the backside deposition metal pair electrode (10) that contacts with black silicon material (8);

Step 2: applying the reverse voltage U that setovers between the first bar shaped metal electrode (1) on black silicon material (8) surface and the metal pair electrode (10) with variable voltage source _-Use semiconductor parametric tester (12) between two any adjacent bullion electrodes of black silicon material (8) surface remainder, to apply a forward voltage bias U simultaneously ₊

Step 3: increase reverse voltage biasing U gradually _-Size, can observe along with reverse voltage biasing U _-Increase, forward voltage bias U ₊Electric current between corresponding remaining any two the bullion electrodes in black silicon material (8) surface reduces gradually, and finally reaches a stationary value; This moment, black silicon/monocrystalline silicon heterojunction was partially anti-fully, and the reverse voltage value of this moment is complete reversed bias voltage value;

Step 4: at the biasing of reverse voltage described in step 2 U _-Be not less than complete reversed bias voltage value described in the step 3; Promptly guarantee under the anti-inclined to one side fully condition of black silicon/monocrystalline silicon heterojunction; Between the bullion electrode of remaining any two different spacing in black silicon material (8) surface, apply constant forward voltage bias with semiconductor parametric tester (12); And measure strength of current, thereby try to achieve the all-in resistance R between the electrode of different interval _m

Step 5: make all-in resistance R _mWith different electric die opening d _nBetween the funtcional relationship straight line, according to the computing formula in the transmission line model method

$R_m=\frac{{\mathrm{\&rho;}}_s{d}_n}{W}+2R_C\&ap;\frac{{\mathrm{\&rho;}}_s}{W}(d+2L_T)$

Can know ρ _sL can be tried to achieve by the slope of said funtcional relationship straight line _TCan try to achieve by the intercept of said funtcional relationship straight line, pass through formula again

${\mathrm{\&rho;}}_c={\mathrm{\&rho;}}_s{L}_T^2=R_c{\mathrm{WL}}_T$

Draw the black silicon material of Ohmic contact and the specific contact resistivity ρ between the metal electrode _c

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